My Unforgettable Encounter with a Fevertree

When someone asks you if you would like to see a wild fever tree, you have to say yes. As a denizen of cold climates defined by months of freezing temperatures, I will never miss an opportunity to encounter any species in its native habitat that cannot survive frosts. This was the scenario I found myself in last week as friend and habitat restoration specialist for the Atlanta Botanical Garden, Jeff Talbert, was showing us around a wonderful chunk of Florida scrubland he has been managing over the last few years.

He drove our small group over to an area that, up until a year or two ago, was completely choked with swamp titi (Cyrilla racemiflora). Like many habitats throughout southeastern North America, this patch of Florida scrub is dependent on regular fires to maintain ecological function. Without it, aggressive shrubs like titi completely take over, choking out much of the amazing biodiversity that makes this region unique. Jeff and his team have been very busy restoring fire to this ecosystem and the results have been impressive to say the least.

We walked off the two-track, down into a wet depression and were greeted by an impressive population of spoon-leaf sundews (Drosera intermedia), which is a good sign that water quality on the site is improving. After a few minutes of sundew admiration, Jeff motioned for us to look upward towards the surrounding tree line. That’s when we saw it. Growing up out of the small seep that was feeding this wet depression was a spindly tree with bright pink splotches decorating its canopy. This was to be my first encounter with a fevertree (Pinckneya bracteata).

A few of us were willing to get our feet wet and were rewarded with a close look at the growth habit of this incredible tree. Clustered at the end of its spindly branches are dark green, ovate leaves that give the tree a tropical appearance. Erupting from the middle of some of those leafy branches were the inflorescences. These are what produce the pink splotches I could see in the canopy of larger individuals. They remind me a lot of a poinsettia and at first, I thought this tree might be a member of the genus Euphorbia. Indeed, the pink coloration comes from a handful of rather large, leaf-like sepals attached to the base of each inflorescence.

Upon seeing the flowers, I instantly knew this was not a member of Euphorbiaceae. Each flower was long and tubular ending in five reflexed lobes. They are colorful structures in and of themselves, adorned with splashes of pink and yellow. After a bit of scrutiny, our group was finally able to place this within its true taxonomic lineage, the coffee family (Rubiaceae).

Within the coffee family, fevertree is closely related to the genus Cinchona. Like Cinchona, the fevertree produces quinine and other alkaloids that are effective in treating malaria. Fevertree has been used for millennia to do just that, hence the common name. It also seems fitting that fevertrees tend to grow in wetland habitats where mosquitos can be abundant. However, this is by no means an obligate wetland species. Those who have grown fevertree frequently succeed in establishing plants in dry, upland habitats as well. Perhaps highly disturbed wetlands are some of the few places where this spindly tree can avoid intense competition from other forms of vegetation.

Fevertrees do need regular disturbance to persist. They are not a large, robust tree by any means and can easily get outcompeted by more aggressive vegetation. However, this species does have a trick that enables individuals to persist when disturbances don’t come frequent enough. Fevertree is highly clonal. Instead of producing a single trunk, it sends out numerous stems in all directions in search of a gap in the canopy. This clonal habit allows it to eek out an existence in the gaps between its more robust neighbors until disturbances return and clear things out.

This clonal habit is also very important when it comes to reproduction. Fevertree requires a decent amount of sunlight to successfully flower and set seed. By using its clonal stems to find light gaps, it can at least guarantee some level of reproduction until fires, floods, or some other form of canopy clearing disturbance frees up enough space for it to prosper and its seeds to germinate. However, its clonal habit can also hurt its reproductive capacity over the long term if recruitment of new individuals does not occur.

Fevertree is considered self-incompatible. In other words, its flowers cannot be pollinated via pollen from a genetically identical individual. As more and more clonal shoots are produced, the tree effectively increases the chances that its own pollen will end up on its own flowers. This is yet another important reason why regular disturbance favors fevertree reproduction. Fevertree seeds need light and bare ground to germinate, which is usually provided as fires and other disturbances clear the canopy and open up bare ground. Only then can enough unrelated individuals establish to ensure plenty of successful pollination opportunities.

With its long, tubular flowers and bright pink sepals, fevertrees don’t seem to have any trouble attracting pollinators, which mainly consist of ruby-throated hummingbirds and bumblebees. Only these organisms have what it takes to successfully access the pollen and nectar rewards of this plant and travel the distances necessary to ensure pollen ends up on unrelated individuals. The seeds that result from pollination are winged and can travel a decent distance with a decent wind. With any luck, a few seeds will end up in another disturbance-cleared wet area and usher in the next generation of fevertrees.

I am so happy that restoration activities at this site are making more suitable habitat for this unique tree. Looking around, we saw many more small individuals starting to emerge where there was once a dense canopy of titi. Hopefully with ongoing management, this population will continue to grow and spread, securing the a future for this species in a region with an ever-growing human presence. If you ever find the opportunity to see one of these trees in person, do yourself a favor and take it!

Further Reading: [1] [2] [3] [4] [5]

Bearcorn: A Mysterious Parasite from Eastern North America

Bearcorn (Conopholis americana) is one of those plants that really challenges mainstream assumptions of what a plant should look like. It produces no leaves, no chlorophyll, and all you ever see of it are its strange reproductive structures. One can easily be forgiven for thinking they had encountered some type of fungus.

Bearcorn is an obligate parasite on oak trees. It simply can’t exist without access to oak roots. From what I have been able to gather, the preferred hosts of bearcorn are the red oaks (section Lobatae). That is not to say the exceptions have not been documented. At least one author claims to have found bearcorn attached to the roots of a white oak (Quercus alba) and even earlier work suggests that American chestnut (Castanea dentata) may have served as an occasional host as well. Regardless, if you want to find bearcorn in the woods, you would do well to search out red oaks first.

According to those who have run germination trials, bearcorn seeds must be in close proximity to oak roots in order to germinate. Some sources say that direct contact is needed whereas others claim that seeds have to be close enough to detect root presence. It is likely that some sort of chemical cue is what initiates the process and this makes sense. For a plant that relies completely on another plant for its water and nutritional needs, it doesn’t make much sense for bearcorn seeds to germinate anywhere but near oak roots.

Upon germinating, the tiny seedling needs to act fast before its meager energy reserves are exhausted. If lucky, the growing seedling will come into contact with an oak root and begin developing a strange organ referred to as the nodule or tubercle. Thus begins its parasitic lifestyle. The tubercle continues to grow throughout the life of the plant, developing into an amorphous, woody blob that continues to envelope more and more oak roots. Its within the tubercle that all of the parasitism takes place.

Cells within the bearcorn tubercle penetrate into the vascular tissues of the oak root, stealing all the water and nutrients the plant will ever need. Over time, the bearcorn tubercle coaxes the roots of the oak to fan outward like the crown of a tiny tree. In doing so, bearcorn is effectively increasing the amount of surface area available to make more parasitic connections. Apparently this all comes at great cost to the oak roots. Over time, oak root size within the tubercle greatly diminishes until some completely perish. Considering the size of some bearcorn populations, one could expect the oak host to fight back.

Indeed, it would appear that oaks are not helpless against bearcorn infestations. Examination of the cells within bearcorn tubercles revealed that as the parasite grows, the oak will begin flooding the infected cells with tannin-rich compounds. Apparently this serves to slow the flow of water and nutrients into the tubercle. There is even evidence that some of those tannins are transferred into the bearcorn tubercle, leading some to suggest that the oak is literally poisoning its bearcorn parasites, albeit slowly.

There is a strong possibility that such oak defenses lend to the relatively short lifespan of bearcorn plants. In at least one study I read, no bearcorn individuals over 13 years of age were found and the average age is estimate to be about 10 years. Perhaps just over a decade is about all a bearcorn can hope for once the its oak host begins to fight back. Good thing bearcorn populations can be surprisingly fecund.

Bearcorn plants reach reproductive maturity at after about 3 years of growth. They flower in the spring and that is when they are at their most obvious. Numerous thick, finger-like stems emerge from the ground covered in whirls of cream-colored, tubular flowers. Though a dense population of flowering bearcorn may look like a bonanza for pollinators, they don’t seem to attract a lot of attention. From what I was able to find, bumblebees are pretty much the only insects to visit the flowers, and even then, visitation rates are low. Apparently bearcorn flowers do not produce any detectable scent nor are they full of nectar. I guess the only real reward is a meager helping of pollen.

Photo by Joshua Mayer licensed under CC BY-SA 2.0

No matter, bearcorn has a nice reproductive trick to ensure plenty of seeds are produced each year - it selfs. The anatomy of the flowers is such that, at maturity, the anthers are in direct contact with the stigma. Even if nothing visits a bloom, it will still go on to clone itself year after year. Once fertilized, each flower gives way to a large fruit chock full of seed. This is where the corn part of the name bearcorn comes from. A stem thick with fruits does resemble a strange, albeit juicy ear of corn sitting on the forest floor. The bear part of the name likely has to do with the fact that bear readily consume bearcorn fruits, stem and all. Working in the southern Appalachian Mountains, I can’t tell you how many times I came across bear scat absolutely loaded with bearcorn fruits and seeds. It’s not just bear either, deer are also very interested in bearcorn fruits.

Lucky for bearcorn, its seeds pass through the guts of these animals unharmed. Hopefully, with a bit of luck, at least one of these animals will make a deposit in an oak-rich region of the forest. With even more luck, some of those seeds might even find themselves nestled in near an oak root to begin the process anew.

Further Reading: [1] [2] [3]

The Future of New Zealand's Shrubby Tororaro Lies in Cultivation

Photo by Jon Sullivan licensed under CC BY-NC 2.0

I was watching a gardening show hosted by one of my favorite gardeners, Carol Klein, when she introduced viewers to a beautiful, divaricating shrub whose branching structure looked like a dense tracery of orange twigs. She referred to the shrub as a wiggy wig and remarked on its beauty and form before moving on to another wonderful plant. I was taken aback by the structure of the shrub and had to learn more. Certainly its form had to be the result of delicate pruning and selective breeding. Imagine my surprise when I found its growth habit was inherent to this wonderful and rare species.

The wiggy wig or shrubby tororaro is known to science as Muehlenbeckia astonii. It is a member of the buckwheat family (Polygonaceae) endemic to grey scrub habitats of eastern New Zealand. Though this species is widely cultivated for its unique appearance, the shrubby tororaro is not faring well in the wild. For reasons I will cover in a bit, this unique shrub is considered endangered. To understand some of these threats as well as what it will take to bring it back from the brink, we must first take a closer look at its ecology.

Photo by WJV&DB licensed under CC BY-SA 3.0

As mentioned, the shrubby tororaro is endemic to grey scrub habitats of eastern New Zealand. It is a long lived species, with individuals living upwards of 80 years inder the right conditions. Because its habitat is rather dry, the shrubby tororaro grows a deep taproot that allows it to access water deep within the soil. That is not to say that it doesn’t have to worry about drought. Indeed, the shrubby tororaro also has a deciduous habit, dropping most if not all of its tiny, heart-shaped leaves when conditions become too dry. During the wetter winter months, its divaricating twigs become bathed in tiny, cream colored flowers that are very reminiscent of the buckwheat family. From a reproductive standpoint, its flowers are quite interesting.

The shrubby tororaro is gynodioecious, which means individual shrubs produce either only female flowers or what is referred to as ‘inconstant male flowers.’ Essentially what this means is that certain individuals will produce some perfect flowers that have functional male and female parts. This reproductive strategy is thought to increase the chances of cross pollination among unrelated individuals when populations are large enough. Following successful pollination, the remaining tepals begin to swell and surround the hard nut at the center, forming a lovely translucent fruit-like structure that entices dispersal by birds. As interesting and effective as this reproductive strategy can be in healthy populations, the shrubby tororaro’s gynodioecious habit starts to break down as its numbers decrease in the wild.

Photo by Jon Sullivan licensed under CC BY-NC 2.0

As New Zealand was colonized, lowland habitats like the grey scrub were among the first to be converted to agriculture and that trend has not stopped. What grey scrub habitat remains today is highly degraded by intense grazing and invasive species. Habitat loss has been disastrous for the shrubby tororaro and its neighbors. Though this shrub was likely never common, today only a few widely scattered populations remain and most of these are located on private property, which make regular monitoring and protection difficult.

Observations made within remnant populations indicate that very little reproduction occurs anymore. Either populations are comprised of entirely female individuals or the few inconstant males that are produced are too widely spaced for pollination to occur. Even when a crop of viable seeds are produced, seedlings rarely find the proper conditions needed to germinate and grow. Invasive grasses and other plants shade them out and invasive insects and rodents consume the few that manage to make it to the seedling stage. Without intervention, this species will likely go extinct in the wild in the coming decades.

Photo by John Pons licensed under CC BY-SA 4.0

Luckily, conservation measures are well underway and they involve cultivation by scientists and gardeners alike. There is a reason this shrub has become very popular among gardeners - it is relatively easy to grow and propagate. From hardwood cuttings taken in winter, the shrubby tororaro will readily root and grow into a clone of the parent plant. Not only has this aided in spreading the plant among gardeners, it has also allowed conservationists to preserve and bolster much of the genetic diversity within remaining wild populations. By cloning, growing, and distributing individuals among various living collections, conservationists have at least safeguarded many of the remaining individuals.

Moreover, cultivation on this scale means dwindling wild populations can be supplemented with unrelated individuals that produce both kinds of flowers. By increasing the numbers within each population, conservationists are also decreasing the distances between female and inconstant male individuals, which means more chances for pollination and seed production. Though by no means out of the proverbial woods yet, the shrubby tororaro’s future in the wild is looking a bit brighter.

This is good news for biodiversity of the region as well. After all, the shrubby tororaro does not exist in a vacuum. Numerous other organisms rely on this shrub for their survival. Birds feed heavily on its fruits and disperse its seeds while the larvae of at least a handful of moths feed on its foliage. In fact, the larvae of a few moths utilize the shrubby tororaro as their sole food source. Without it, these moths would perish as well. Of course, those larvae also serve as food for birds and lizards. Needless to say, saving the shrubby tororaro benefits far more than just the plant itself. Certainly more work is needed to restore shrubby tororaro habitat but in the meantime, cultivation is ensuring this species will persist into the future.

Further Reading: [1] [2] [3]

The Ceropegias Welcome a New Member

Photos by David Styles

The genus Ceropegia is home to some of my favorite plants. Not only are they distant cousins of the milkweeds (Asclepias spp.), they sport some of the most interesting floral morphologies whose beauty is only exceeded by their fascinating pollination syndromes. Recently, Ceropegia expert and friend of the podcast Dr. Annemarie Heiduk brought to my attention the recent description of a species named in her honor.

Ceropegia heidukiae hails from KwaZulu-Natal, South Africa, and, at current, is believed to be endemic to a habitat type called the Northern Zululand Mistbelt Grassland. Morphologically, it has been described as an erect perennial herb. Unlike many of its cousins, C. heidukiae does not vine. Instead, it grows a slender stem with opposite, ovate leaves that just barely reaches above the surrounding grasses. By far the most striking feature of this plant are its flowers.

Photos by David Styles.

Ceropegia heidukiae produces elaborate trap flowers at the tips of its slender stems during the month of December (summer in the Southern Hemisphere). Each flower is comprised a greenish-gold, striped tube made of fused petals and topped with a purple, star-like structure with fine hairs. These flowers were the key indication that this species was previously unknown to science. Additionally, a sweet, acidic scent was detected during the relatively short blooming period.

Their beauty aside, the anatomy and scent of these flowers hints at what may very well be a complex and specific pollination syndrome. Indeed, scientists like Dr. Heiduk are revealing amazing chemical trickery within the flowers of this incredible genus, including one species that mimics the smell of dying bees. Who knows what kinds of relationships this new species has evolved in its unique habitat. Only plenty of observation and experimentation will tell and I anxiously await future studies.

A view of the Northern Zululand Mistbelt Grassland where Ceropegia heidukiae was found.

Sadly, C. heidukiae lives in one of South Africa’s most threatened habitat types. South Africa’s Biodiversity Act currently classifies the Northern Zululand Mistbelt Grassland as endangered due to factors like timber plantations and unsustainable grazing. Hopefully with the recognition of unique species like C. heidukiae, more attention can be given to sustainable use of the Northern Zululand Mistbelt Grassland such that both the people and the species that rely on it can continue to do so for generations to come.

Photo Credits: David Styles

Further Reading: [1] [2]

Native Plants Make Every Day Earth Day

We get so much joy out of watching people take pictures of our gardens as they walk by our apartment.

Spring is here in the Northern Hemisphere which means gardening season is well underway. Having spent all winter thinking about what kinds of native plants we want to add to our gardens, my partner and I are always very excited to start germinating seeds and propagating plants. Though we always place the plants at the center of our focus, we would be lying if we said a big part of our gardening obsession wasn’t aimed at attracting wildlife to our property.

There is no denying that gardening, especially with native plants, is the best way to benefit local wildlife in your neighborhood. It doesn’t take much to succeed either. Our landlords are amazing people that allow us a certain degree of freedom to do what we wish with the yard, but they still want to ensure that we maintain something akin to a “traditional” suburban landscape. As such, most of our gardening efforts must be crammed into borders and other highly manicured areas surrounding the lawn. Even so, we are constantly amazed by how much life our plants attract.

I really wish we had the foresight to document insect diversity before we began planting so we could do a before and after comparison, but hindsight is always 20/20. From bees to mantis flies and a hefty population of fireflies, we spend hours each week pursuing the garden to see what kinds of interesting critters are hanging around the yard. The amount of insect life in our garden hasn’t gone unnoticed either.

Leafhoppers and treehoppers are among our favorite insects to see in our gardens.

I remember one afternoon a couple years back, our neighbor approached us to ask if we had seen any bees visiting our tomato plants. Our reply was a very enthusiastic “YES” followed by a rundown of our best estimates on how many different bee species we encountered each day. He seemed a bit bummed and replied that he had yet to see a single bee on his plants. This was a teaching moment that we needed to address as tactfully as possible.

You see, this neighbor is obsessed with mowing and spraying. Save for a few irises near his front porch and two raised beds chock full of tomatoes, no other plants beside grass are allowed to establish on his property. Though completely anecdotal, I can’t help but feel his lack of plants translates in a big way to his lack of bees. We mentioned that all of those “weeds” in our yard that he is always “jokingly” giving us a hard time about are the reason that we have so many bees. Tomato flowers are great but they aren’t around all the time and bees need other food to survive. They also need places to reproduce, which means leaving bare patches of soil around the property and allowing plenty of garden debris in the form of stems, twigs, and leaves to remain in place well into summer.

I am not sure we convinced him to completely change his ways with that conversation, but it definitely got him thinking. He asked if next time we have some spare plants if we wouldn’t mind donating a few so that he can plant them near his tomato beds. We enthusiastically agreed. Though a minor victory, we celebrated the fact that our garden had served as a mini catalyst for a tiny change in someone else’s life.

A firefly stopping for a sip of nectar on one of our common milkweeds (Asclepias syriaca).

With Earth Day coming up this week, the internet is full of quick tips on how to make your life more eco-friendly. There are endless articles available to those looking for advice on green living and sustainable gift ideas. I would like to argue that there is no greener gift than the gift of native plants. It doesn’t matter which species or why, just make sure you pick plants that are native to your region. By establishing native plants in your garden or even in pots on your patio or balcony, you are making a great step in celebrating Earth Day every day. Plants are truly the gift that keeps on giving and you can sleep better at night knowing that they are doing so much more than simply beautifying a space. They are providing food, shelter, and a place to breed for the countless organisms that allow ecosystems to function.

And, as we experienced with our neighbor, native plants can offer so many wonderful moments of inspiration and learning. As I discuss in my book, “In Defense of Plants: An Exploration into the Wonder of Plants,” realizing that native plants and the communities they comprise set the foundation for all other life on this planet set me on a path of wonder and discovery that I have never left. Plants changed my life for the better and by surrounding ourselves with them at all times, my partner and I know that we are doing our part to change the lives of the many organisms struggling to survive in this human-dominated world. So, if you want to live every day like it’s Earth Day, brighten up your life with a few native plants and enjoy all of the wonder and beauty they provide.

Some Magnolia Flowers Have Built-In Heaters

Magnolia denudata. Photo by 阿橋 HQ licensed under CC BY-SA 2.0

There are a lot of reasons to like magnolias and floral thermogenesis is one of them. That’s right, the flowers of a surprising amount of magnolia species produce their own heat! Although much more work is needed to understand the mechanisms involved in heat generation in these trees, research suggests that it all centers on pollination.

Magnolias have a deep evolutionary history, having arose on this planet some 95+ million years ago. Earth was a very different place back then. For one, familiar insect pollinators like bees had not evolved yet. As such, the basic anatomy of magnolia flowers was in place long before bees could work as a selective pressure in pollination. What were abundant back then were beetles and it is thought that throughout their history, beetles have served as the dominant pollinators for most species. Indeed, even today, beetles dominate the magnolia pollination scene.

Magnolia sprengeri. Photo by Aleš Smrdel licensed under CC BY-NC 2.0

Beetles are generally not visiting flowers for nectar. They are instead after the protein-rich pollen within each anther. It seems that when the anthers are mature, beetles are very willing to spend time munching away within each flower, however, keeping their attention during the female phase of the flower is a bit trickier. Because there are no rewards for visiting a magnolia flower during its female phase, evolution has provided some species with an interesting trick. This is where heat comes in.

Though it varies from species to species, thermogenic magnolias produce combinations of scented oils that various beetles species find irresistible. That is, if they can pick up the odor against the backdrop of all the other enticing scents a forest has to offer. By observing floral development in species like Magnolia sprengeri, researchers have found that as the flowers heat up, the scented oils produced by the flower begin to volatilize. In doing so, the scent is dispersed over a much greater area than it would be without heat.

Magnolia tamaulipana. Photo by James Gaither licensed under CC BY-NC-ND 2.0

Unlike some other thermogenic plants, heat production in magnolia flowers doesn’t appear to be constant. Instead, flowers experience periodic bursts of heat that can see them reaching temperatures as high as 5°C warmer than ambient temperatures. These peaks in heat production just to happen to coincide with the receptivity of male and female organs. Also, only half of the process is considered an “honest signal” to beetles. During the male phase, the beetles will find plenty of pollen to eat. However, during the female phase, the scent belies the fact that beetles will find no reward at all. This has led to the conclusion that the non-rewarding female phase of the magnolia flower is essentially mimicking the rewarding male phase in order to ensure some cross pollination without wasting any energy on additional rewards.

The timing of heat production also changes depending on the species of beetle and their feeding habits. For species like the aforementioned M. sprengeri, which is pollinated by beetles that are active during the day, heat and scent production only occur when the sun is up. Alternatively, for species like M. tamaulipana whose beetle pollinators are nocturnal, heat and scent production only occur at night. Researchers also think that seasonal climate plays a role as well, suggesting that heat itself may be its own form of pollinator reward in some species. Many of the thermogenic magnolias bloom in the early spring when temperatures are relatively low. It is likely that, aside from pollen, beetles may also be seeking a warm spot to rest.

Personally, I was surprised to learn just how many different magnolias are capable of producing heat in their flowers. When I first learned of this phenomenon, I thought it was unique to M. sprengeri but I was wrong. We still have a lot to learn about this process but research like this just goes to show you that even familiar genera can hold many surprises for those curious enough to seek them out.

Further Reading: [1] [2] [3] [4] [5]

Meet the Golden Lotus Banana

Photo by Linda De Volder licensed under CC BY-NC-ND 2.0

While perusing the internet the other day, I scrolled past an image of what looked like the physical manifestation of the sun emoji on my phone. The bright yellow flash was so striking that it caused me to pause and scroll back to the source. I was pleasantly surprised to see that the sun-like object belonged to something botanical. I was even more surprised to find out that it was produced by a unique cousin of the banana called the golden lotus banana (Musella lasiocarpa).

The golden lotus banana is an oddball in many ways. For starters, it has a confusing taxonomic history. For many years, this odd plant has bounced back and forth between what was originally the only two genera in the banana family (Musaceae). Indeed, it has many outward characteristics that could firmly land it in either the genus Musa or the genus Ensete. Still, this plant is strange enough that numerous taxonomists have taken their own stab at narrowing down its correct placement. It wasn’t until DNA analyses revealed it to be so distinct from either of these genera that it warranted its own unique taxonomic placement. Thus, the monotypic genus Musella was born.

Photo by FarOutFlora licensed under CC BY-NC-ND 2.0

The plant itself is well known and widely cultivated throughout its home range in the Yunnan province of China. In fact, the golden lotus banana is so widely cultivated in this region as food for both humans and cattle alike, that experts couldn’t quite figure out if there were any wild populations left. It wasn’t until relatively recently that some wild populations were found. Sadly, these populations are under threat of being completely extirpated as much of the conifer-oak forests it calls home have been highly fragmented and degraded due to human activities. At least its popularity in cultivation means this species is not likely to go completely extinct any time soon.

The golden lotus banana is rather interesting in form. When you look for pictures of this species around the web, you are likely to pull up images of a stubby, nearly leafless stalk tipped with the bright yellow bracts that look like the rays of a cartoonish sun. Apparently, plants can lose many of their leaves in cultivation around the time the inflorescence matures, giving the impression that it never had any to begin with. Of course, the plant does produce typical banana-like leaves for most of the year. As mentioned, the amazing inflorescence is borne at the tip of what looks like a small, woody trunk, but in reality is actually the fused petioles of their leaves. All members of the banana family are, after all, overgrown herbs, not trees.

As is typical with this family, the flowers don’t all ripen at once. Instead, they begin at the base and gradually ripen over time, revealing consecutive whirls of tubular flowers surrounded by bright yellow bracts, though a variant population that produces red bracts was recently described as well. Interestingly, the golden lotus banana differs from its banana cousins in that its flowers are not pollinated by bats or birds. Instead, bees and wasps comprise the bulk of floral visitors, at least among cultivated populations. The first flowers to mature are male flowers that produce a small amount of nectar and copious amounts of pollen. Only the flowers near the base of the inflorescence are female and they produce a lot more nectar than the male flowers.

Photo by Linda De Volder licensed under CC BY-NC-ND 2.0

Research has shown that bees are far more likely to visit female over male flowers and their visits to female flowers last much longer. This is likely due to the differences in nectar production, but the end result is that by encouraging bees to spend less time on male flowers and more time on female flowers, each plant greatly increases the chances that pollen of unrelated individuals will end up on the stigma. After pollination, tiny fruits are formed, however, from what I have read they are largely inedible to humans. Once the fruits ripen and seeds are dispersed, the flowering stalk dies back and is replace by a fresh new growth stalk from the underground rhizome.

The next time you find yourself at a botanical garden with a decent tropical plant collection, keep an eye out for the golden lotus banana. Outside of China, this species has gained some popularity among specialist plant growers and you just might be lucky to stumble across one in the process of blooming.

Further Reading: [1] [2] [3]

A Closer Look at Hyacinths

Photo by Radu Chibzii licensed under CC BY-SA 2.0

They say that our sense of smell is very closely tied with the formation of memories. It is around this time of year that I am strongly reminded of the power of that link. All I have to do is catch a whiff of a blooming hyacinth and I am immediately transported back to childhood where spring time gatherings with the family were always accompanied by mass quantities of these colorful bulbs. Indeed, the smell of hyacinths in bloom will forever hold a special place in my mind (and heart).

Because it is spring in my neck of the woods and because my partner recently came home with a wonderful potted hyacinth to add some springy joy our apartment, I decided to take a dive into the origins of these plants. Where do they come from and how do they live in the wild? Certainly they didn’t originate in our gardens.

To start with, there are surprisingly few true hyacinths in this world these days. Whereas many more spring flowering bulbs were once considered members, today the genus Hyacinthus is comprised of only three species, H. litwinovii, H. transcaspicus, and the most famous of them all, H. orientalis. All other “hyacinths” are hyacinths in name only. These plants were once considered members of the lily family (Liliaceae) but more recent genetic work places them in the asparagus family (Asparagaceae).

All three species of hyacinth are native to the eastern Mediterranean region, throughout the Middle East, and well into southwestern Asia. As you might imagine, there is a fair amount of geographical variation across populations of these plants. For instance, H. orientalis itself contains many putative subspecies and varieties. However, their long history of human cultivation has seen them introduced and naturalized over a much wider area of the globe. Generally speaking, these plants tend to prefer cool, higher elevation habitats and loose soils.

As many of you already know, hyacinths are bulbous plants. Throughout most of the year, they lie dormant beneath the soil waiting for warming spring weather to signal that it’s growing time. And grow they do! Because their leaves and inflorescence are already developed within the bulb, hyacinths can rapidly emerge, flower, and leaf out once snow thaws and releases water into the soil. And flower they do! Though selective breeding has resulted in myriad floral colors and strong, pleasant odors, the wild species are nonetheless put on quite a display.

The flowers of wild hyacinths are generally fewer in number and can range in color from almost white or light blue to nearly purple. Their wonderful floral scent is not a human-bred characteristic either, though we have certainly capitalized on it in the horticulture trade. In the wild, these scent compounds call in pollinators who are rewarded with tiny amounts of nectar. It is thought that bees are the primary pollinators of hyacinths both in their native and introduced habitats.

Of course, all of their floral beauty comes down to seed production. Upon ripening, each fruit (capsule) opens to reveal numerous seeds, each with a fleshy attachment called an elaiosome. The elaiosome is very attractive to resident ants that quickly go to work collecting seeds and bringing them back to their colony. However, it isn’t the seed itself the ants are interested in, but rather the elaiosome. Once it is removed and consumed, the seed is discarded, usually in a waste chamber within the colony where it is free to germinate far away from potential seed predators.

Once growth and reproduction are over, hyacinths once again retreat back underground into their bulb phase. Amazingly, these plants have a special adaptation to make sure that their bulbs are tucked safely underground, away from freezing winter temperatures. Throughout the growing season, hyacinths produce specialized roots that are able to contract. As they contract, they literally pull the base of the plant deeper into the soil. This is very advantageous for plants that enjoy growing in loose soils that are prone to freezing. Once underground and away from frost and snow, they lie dormant until spring returns.

I don’t know about you but getting to know how common garden plants like hyacinths make a living in the wild only makes me appreciate them more. I hope this brief introduction will have you looking at the hyacinths in your neighborhood in a whole new light.

Further Reading: [1] [2]

When the Going Gets Tough, Desert Mistletoes Cooperate

Sure, parasites can be a drain on their host, but for those parasites whose entire life depends on a living host, it doesn’t pay to kill. Such is the case for the desert mistletoe (Phoradendron californicum). These plants simply can’t live without the water and nutrients they receive from their host trees. But what happens when more than one mistletoe infects a single tree? One would think that supporting multiple mistletoes would be a dangerous drain on the host tree. However, recent research based in the Sonoran Desert suggests that desert mistletoe has a trick up its stems that involves a bit of communication with its neighbors.

Desert mistletoe isn’t completely reliant on its host for all of its nutritional needs. Though lacking leaves, the desert mistletoe is fully capable of photosynthesis via its tangled mass of green stems. Most of what desert mistletoes extract from their host consists of water and other nutrients they can’t acquire themselves. However, desert mistletoes rarely operate alone. Thanks to their nutritious berries and the territorial habits of the birds that disperse them, multiple mistletoe individuals often wind up parasitizing the same tree.

Heavy infestations may sound like a death sentence for the host tree, especially in the harsh Sonoran climate. However, by manipulating the mistletoe loads on various trees and observing how mistletoes and their hosts respond, researchers have discovered that mistletoes can apparently sense their neighbors and alter their behavior accordingly.

During dry periods, trees become stressed for both water and nutrients. For mistletoes growing on a stressed tree, it doesn’t make much sense from an evolutionary standpoint to increase their demand on the host during these times. Instead, mistletoes growing on stressed trees actually increased the amount of photosynthesis they perform without increasing the amount of water they extract from their host. By altering their metabolism in this way, the mistletoes do not add any extra burden to their already stressed host tree but nonetheless maintain their own fitness.

Amazingly, the situation got even more interesting when researchers experimentally removed some mistletoes. Somehow, depending on their position on their host tree, some remaining mistletoes can sense that their competitors had been removed. When this happens, they don’t go into overdrive and start exacting a greater share of resources from their host. Instead, the remaining mistletoe appear to sense that they no longer have to compete as much and adjust their water and nutrient uptake in such a way that actually allows their host to benefit as well.

Certainly these findings generate more questions than they answer. First, how do mistletoes sense their neighbors? Given their direct links with the host vascular tissues, they could be sensing signals from other parasites that way. There is also the potential for airborne signal detection as well. Also, do mistletoes behave differently when growing near related individuals versus strangers? What researchers have ultimately uncovered is a fascinating coevolutionary system in desperate need of more attention.

Further Reading: [1]

How Fungus Gnats Maintain Jack-in-the-pulpits

[SOURCE]

There are a variety of ways that the boundaries between species are maintained in nature. Among plants, some of the best studied examples include geographic distances, differences in flowering phenology, and pollinator specificity. The ability of pollinators to maintain species boundaries is of particular interest to scientists as it provides excellent examples of how multiple species can coexist in a given area without hybridizing. I recent study based out of Japan aimed to investigate pollinator specificity among fungus gnats and five species of Jack-in-the-pulpit (Arisaema spp.) and found that pollinator isolation is indeed a very strong force in maintaining species identity among these aroids, especially in the wake of forest disturbance.

Fungus gnats are the bane of many a houseplant grower. However, in nature, they play many important ecological roles. Pollination is one of the most underappreciated of these roles. Though woefully understudied compared to other pollination systems, scientific appreciation and understanding of fungus gnat pollination is growing. Studying such pollination systems is not an easy task. Fungus gnats are small and their behavior can be very difficult to observe in the wild. Luckily, Jack-in-the-pulpits often hold floral visitors captive for a period of time, allowing more opportunities for data collection.

By studying the number and identity of floral visitors among 5 species of Jack-in-the-pulpit native to Japan, researchers were able to paint a very interesting picture of pollinator specificity. It turns out, there is very little overlap among which fungus gnats visit which Jack-in-the-pulpit species. Though researchers did not analyze what exactly attracts a particular species of fungus gnat to a particular species of Jack-in-the-pulpit, evidence from other systems suggests it has something to do with scent.

Like many of their aroid cousins, Jack-in-the-pulpits produce complex scent cues that can mimicking everything from a potential food source to a nice place to mate and lay eggs. Fooled by these scents, pollinators investigate the blooms, picking up and (hopefully) depositing pollen in the process. One of the great benefits of pollinator specificity is that it greatly increases the chances that pollen will end up on a member of the same species, thus reducing the chances of wasted pollen or hybridization.

Still, this is not to say that fungus gnats are solely responsible for maintaining boundaries among these 5 Jack-in-the-pulpit species. Indeed, geography and flowering time also play a role. Under ideal conditions, each of the 5 Jack-in-the-pulpit species they studied tend to grow in different habitats. Some prefer lowland forests whereas others prefer growing at higher elevations. Similarly, each species tends to flower at different times, which means fungus gnats have few other options but to visit those blooms. However, such barriers quickly break down when these habitats are disturbed.

Forest degradation and logging can suddenly force many plant species with different habitat preferences into close proximity with one another. Moreover, some stressed plants will begin to flower at different times, increasing the overlap between blooming periods and potentially allowing more hybridization to occur if their pollinators begin visiting members of other species. This is where the strength of fungus gnat fidelity comes into play. By examining different Jack-in-the-pulpit species flowering in close proximity to one another, the team was able to show that fungus gnats that prefer or even specialize on one species of Jack-in-the-pulpit are not very likely to visit the inflorescence of a different species. Thanks to these preferences, it appears that, thanks to their fungus gnat partners, these Jack-in-the-pulpit species can continue to maintain species boundaries even in the face of disturbance.

All of this is not to say that disturbance can’t still affect species boundaries among these plants. The researchers were quick to note that forest disturbances affect more than just the plants. When a forest is logged or experiences too much pressure from over-abundant herbivores such as deer, the forest floor dries out a lot quicker. Because fungus gnats require high humidity and soil moisture to survive and reproduce, a drying forest can severely impact fungus gnat diversity. If the number of fungus gnat species declines, there is a strong change that these specific plant-pollinator interactions can begin to break down. It is hard to say what affect this could have on these Jack-in-the-pulpit species but a lack of pollinators is rarely a good thing. Certainly more research is needed.

Photo Credit: [1]

Further Reading: [1]

My New Book Has Arrived!

The time has finally come! In Defense of Plants: An Exploration into the Wonder of Plants is now in stores. I thank everyone who pre-ordered a copy of the book. They should be on their way! I still can’t believe this is a reality. I always knew I wanted to write a book and I am eternally grateful to Mango Publishing for giving me this opportunity.

In Defense of Plants is a celebration of plants for the sake of plants. There is no denying that plants are extremely useful to humanity in many ways, but that isn’t why this exist. Plants are living, breathing, self-replicating organisms that are fighting for survival just like the rest of life on Earth. And, thanks to their sessile habit, they are doing so in remarkable and sometimes alien ways.

One of the best illustrations of this can be found in Chapter 3 of my new book: “The Wild World of Plant Sex.” Whereas most of us will have a passing familiarity with the concept of pollination, we have only really scratched the surface of the myriad ways plants have figured out how to have sex. Some plants go the familiar rout, offering pollen and nectar to floral visitors in hopes that they will exchange their gametes with another flower of the same species.

Others have evolved trickier means to get the job done. Some fool their pollinators into thinking they are about to get a free meal using parts of their anatomy such as fake anthers or by offering nectar spurs that don’t actually produce nectar. Some plants even pretend to smell like dying bees to lure in scavenging flies. Still others bypass food stimuli altogether and instead smell like receptive female insects in hopes that sex-crazed males won’t know the difference.

Pollination isn’t just for flowering plants either. In In Defense of Plants I also discuss some of the novel ways that mosses have converged on a pollination-like strategy by co-opting tiny invertebrates that thrive in the humid microclimates produced by the dense, leafy stems of moss colonies.

This is just a taste of what is printed on the pages of my new book. I really hope you will consider picking up a copy. To those that already have, I hope you enjoy the read when it arrives! Thank you again for support In Defense of Plants. You are helping keep these operations up and running, allowing me to continue to bring quality, scientifically accurate botanical content to the world. Thank you from the bottom of my heart.

Click here if you would like to order a copy!

You can also purchase a copy directly from the publisher

Goblin's Gold: the story of a luminous moss

Photo by Alpsdake licensed under CC BY-SA 4.0

Luminous moss, dragon’s gold, goblin’s gold… when a moss has this many common names, you know it must catch the eye. Indeed, Schistostega pennata might just be one of the most dazzling of mosses around, that is provided you know where and how to look for it.

Let’s begin with a brief introduction. Goblin’s gold is the only member of both its genus (Schistostega) and family (Schistostegaceae). Despite its unique taxonomic position, it is nonetheless a widespread species, growing naturally throughout many temperate regions of the Northern Hemisphere.

When fully grown, the gametophyte stage of goblin’s gold sort-of resembles a tiny, green, semi-translucent feather. Small spore capsules are borne on the spindly stalk of the sporophyte and the resulting spores are said to be quite sticky. Instead of relying on wind to disperse its propagules, golbin’s gold utilizes animals. The spores are sticky enough that they get glom onto any insects or other small animals that brush up against them.

The mature gametophyte of Schistostega pennata. Photo by HermannSchachner licensed under Public Domain

None of this, however, gives a hint as to how it earned all of those colorful names. To find that out, one must be ready to brave dark, damp spaces like caves. You see, though it can grow in more open habitats, you are most likely to encounter goblin’s gold in dark crevices or under overhangs. It has been said that goblin’s gold does not compete well with other plants in most habitats, but that doesn’t mean it doesn’t have a few tricks up its stems that give it an edge in other types of habitats.

For most plants, caves and other dark places are a no go. They simply can’t get enough light to survive. Such is not the case for goblin’s gold. Instead of trying to compete with more aggressive vegetation, goblin’s gold occupies deeply shaded habitats that few other plants can. It owes its shade-tolerant abilities to a stage of its development most of us rarely think about, let alone notice.

Photo by Jymm licensed under CC BY-SA 4.0

When a moss spore germinates, it doesn’t immediately look like what we would recognize as a moss. Instead, it grows into thread-like, multicellular fillaments called a “protonema.” You can think of this as the juvenile stage of the gametophyte. The protonema spreads outward as it grows, gradually producing hormones and other growth regulators that will control the development of the mature gametophyte. Because goblin’s gold grows in such dark habitats, it can’t afford to grow its gametophyte anywhere. To grow long enough to reproduce, it has to find spots where there is enough light to complete its lifecycle.

This is where the protonema comes in. In much the same why that fungal hyphae fan out into the soil in search of food to decompose, goblin’s gold protonema fan out over the damp substrate, searching for spots where enough light filters through to fuel growth. Luckily, the protonema can make do with much less light that the mature gametophyte, which also happens to be how this tiny moss earned so many interesting nicknames.

When grown in deep shade, the protonema of goblin’s gold develops a layer of lens-shaped cells on its surface. The opposite side of each cell narrows to a cone. When light, no matter how weak, strikes these lens cells, the curvature focuses the light down into the cell so that it is concentrated into the tip at the bottom. Being able to sense the direction of the light, the chloroplasts within each cell can actually move around so that they are always in a position that maximizes their exposure. Through this process, each cell is able to concentrate what little light is available so that they can photosynthesize in light so low that nearly all other plants will starve.

[SOURCE]

The light concentrating mechanism of the goblin’s gold protonema happens to have a wonderful and stunning side effect. As light enters the lens, small amounts of it are refracted around the cell. When that refracted light mixes with the green light that isn’t absorbed by the chloroplasts, it bounces back into the environment, giving the whole protonemal mat a green florescent glow when viewed in just the right way.

By being able to make use of what little light finds its way into these dark habitats, goblin’s gold can grow largely free of competition. Also, the protonema itself is capable of asexual reproduction so colonies can grow to epic proportions in dark areas, only producing mature gametophytes in a few spots. Interestingly, there appears to be some plasticity to this light-concentrating habit as well. When observing goblin’s gold protonema that develop under high light conditions, researchers have found that they do not develop lens shaped cells and therefore are not capable of reflecting light in the same way.

Humans have known about this moss for centuries, even if they didn’t understand the mechanisms that cause it, and that is why this wonderfully unique species has earned so many common names.

Photo Credits: [1] [2] [3] [4]

Further Reading: [1] [2] [3] [4]

The First Genus (Alphabetically)

Photo by Eric in SF licensed under CC BY-SA 3.0

One thing I love about orchids is that they are so diverse. One could spend their entire life studying these plants and never run out of surprises. Every time I sit down with an orchid topic in mind, I end up going down a rabbit hole of immeasurable depth. I love this because I always end up learning new and interesting facts. For instance, I only recently learned that there is a genus of orchids that has been given the unbelievably complex name of Aa.

No, that is not an abbreviation. The genus was literally named Aa. As far as I have been able to tell, it is pronounced “ah” rather than “ay,” but if any linguists are reading this and beg to differ, please chime in! Regardless, I was floored by this silly exercise in plant naming and had to learn more. I had never heard of this genus before and figured that it was so obscure that it probably contained, at most, only a small handful of species. This assumption was wrong.

Aa maderoi. Photo by Dr. Alexey Yakovlev licensed under CC BY-SA 2.0

Though by no means massive, the genus Aa contains at least 25 recognized species. A quick search of the literature even turned up a few relatively recent papers describing new species. Apparently we have a ways to go in understanding their diversity. Nonetheless, this is an interesting and pretty genus of orchids.

From what I gather, Aa are most often found growing at high elevations in the Andes, though at least one species is native to mountainous areas of Costa Rica. They are terrestrial orchids that prefer cooler temperatures and fairly moist soil. Some species are said to only be found in close proximity to mountain streams. Some of the defining features of the genus are a tall inflorescence jam packed with tiny inconspicuous, greenish-white flowers. The flowers are surrounded by semi-transparent sheaths that are surprisingly showy. All in all, they kind of remind me of a mix between Spiranthes and Goodyera.

Close up of an inflorescence of Aa maderoi showing the small, white flowers and large, semi-transparent sheaths. Photo by Dr. Alexey Yakovlev licensed under CC BY-SA 2.0

But what about the name? Why in the world was this genus given such a strange and abrupt moniker? The answer seems to be the silliest option I could think of: to be first. This genus was originally described in 1845 by German botanist Heinrich Gustav Reichenbach who recognized two species within the genus Altensteinia to be distinct enough to warrant their own genus.

According to most sources I could find, he coined this new genus Aa so that it would appear first on all taxonomic lists. There is at least one other report that the name was given in honor of a man by the name of Pieter van der Aa, but apparently this is “highly” disputed. However, all of this should be taken with a grain of salt. Though I can find plenty of literature describing various species within the genus, I could turn up no actual literature on the naming of the genus itself. All I could find is what has been repeated (almost verbatim) from Wikipedia.

So, there you have it. Not only does the genus Aa exist, it is still top of the list of all plant genera. If that truly was the goal Heinrich Gustav Reichenbach was aiming for, he certainly has succeeded!

Photos via Wikimedia Commons

Further Reading: [1]

A Newly Described Fungus That Mimics Flowers

(A) Young yellow-orange pseudoflower. (B) Mature pseudoflower. (C) Longitudinal section of an infected X. surinamensis inflorescence. (D) Healthy yellow flower of X. surinamensis shown for comparison. [SOURCE]

Imagine there was a fungus that was able to hijack human reproductive structures so that it could reproduce. Though this sounds like the basis of a strange science fiction story, a similar situation to this has just been described from Guyana between two species of yellow-eyed grass (Xyris setigera & X. surinamensis) and a newly described species of fungus called Fusarium xyrophilum.

Fungi that hijack plant reproductive systems are pretty rare in nature, especially when you consider the breadth of interactions between these two branches on the tree of life. What makes this newly described case of floral hijacking so remarkable is the complexity of the whole process. It all begins when an infected Xyris host begins to produce its characteristically lanky inflorescence.

At first glance, nothing would appear abnormal. The floral spike elongates and the inflorescence at the tip gradually matures until the flowers are ready to open. Even when the “flower” begins to emerge from between the tightly packed bracts the process seems pretty par for the course. Gradually a bright yellow, flower-like structure bursts forth, looking very much like how a bright yellow Xyris flower should look. However, a closer inspection of an infected plant would reveal something very different indeed.

Instead of petals, anthers, and a pistil, infected inflorescences produce what is called a pseudoflower complete with petal-like structures. This pseudoflower is not botanical at all. It is made entirely by the Fusarium fungus. Amazingly, these similarities are far from superficial. When researchers analyzed these pseudoflowers, they found that they are extremely close mimics of an actual Xyris flower in more than just looks. For starters, they produce pigments that reflect UV light in much the same way that actual flowers do. They also emit a complex suite of volatile scent compounds that are known to attract pollinating insects. In fact, at least one of those compounds was an exact match to a scent compound produced by the flowers of these two Xyris species.

So, why would a fungus go through all the trouble of mimicking its hosts flowers so accurately? For sex, of course! This species of Fusarium cannot exist without its Xyris hosts. However, Xyris don’t live forever and for the cycle to continue, Fusarium must go on to infect other Xyris individuals. This is where those pseudoflowers come in. Because they so closely match actual Xyris flowers in both appearance and smell, pollinating bees treat them just like flowers. The bees land on and investigate the fungal structure until they figure out there is no reward. No matter, they have already been covered in Fusarium spores.

As the bees visit other Xyris plants in the area, they inevitably deposit spores onto each plant they land on. Essentially, they are being coopted by the fungus in order to find new hosts. By mimicking flowers, the Fusarium is able to hijack plant-pollinator interactions for its own reproduction. It is not entirely certain at this point just how specific this fungus is to these two Xyris species. A search for other potential hosts turned up only a single case of it infecting another Xyris. It is also uncertain as to how much of an impact this fungus has on Xyris reproduction. Though the fungus effectively sterilizes its host, researchers did make a point to mention that Xyris populations may actually benefit from having a few infected plants as the pseudoflowers last much longer than the actual flowers and therefore could serve to attract more pollinators to the area over time. Who knows what further investigations into the ecology of this bizarre system will reveal.

Photo Credit: [1]

Further Reading: [1]

The Ancient Green Blobs of the Andes

Photo by Atlas of Wonders licensed under CC BY-NC-ND 2.0

Curious images of these strange green mounds make the rounds of social media every so often. What kind of alien life form is this? Is it a moss? Is it a fungus? The answer may surprise you!

These large, green mounds are comprised of a colony of plants in the carrot family! The Yareta, or Azorella compacta, hails from the Andes and only grows between 3,200 and 4,500 meters (10,500 - 14,750 ft) in elevation. Its tightly compacted growth habit is an adaptation to its high elevation lifestyle. Cushion growth like this helps these plants prevent heat and water loss in these cold, dry, windy environments.

Every so often, these mats erupt with tiny flowers, which must be a sight to behold! Photo by Lon&Queta licensed under CC BY-NC-SA 2.0

As you might imagine, these plants are extremely slow growers. By studying their growth rates over time, experts estimate that individual colonies expand at the rate of roughly 1.5 cm each year. By extrapolating these rates to the measurements of large colonies, we get a remarkable picture of how old some of these plants truly are. Indeed, some of the largest colonies are estimated at over 3000 years old, making them some of the oldest living organisms on the planet!

Sadly, the dense growth of the plant makes it highly sought after as a fuel source. Massive chunks of these plants are harvested with pick axes and burned as a source of heat. Due to their slow growth rate, overharvesting in recent years has caused a serious decline in Yareta populations. Local governments have since enacted laws to protect this species in hopes that it will give colonies the time they need to recover. Indeed, some recovery has already been documented, however, continued monitoring and management will be needed to ensure their populations remain viable into the foreseeable future.

Photo Credits: [1] [2]

Further Reading: [1] [2] [3]

Book Release Updates!

It’s February, which means In Defense of Plants: An Exploration into the Wonder of Plants comes out this month!! I just wanted to give you all an update on when orders will start shipping.

Due to shipping delays, physical book orders will not begin shipping until February 23rd from all retailers. I apologize for the week-long delay, but COVID has done a number on shipping logistics and the publisher is doing all they can. Stay patient and you will get it within that week.

Also, for those in Europe, North and South East Asia, Oceania, and Canada that are interested in purchasing a copy, In Defense of Plants will be available in those markets as well! Please stay tuned for more availability info.

That being said, anyone who pre-ordered the audio book or ebook version will receive their copy as scheduled on February 16th.

Finally, a massive thank you to everyone who has pre-ordered the book thus far. Your interest has skyrocketed In Defense of Plants to the top of multiple new release lists! For those of you interested in getting their hands on a copy, here are some links:

Amazon- https://amzn.to/3mBA1Ov

Bookshop- https://bit.ly/3lxih5B

Barnes and Noble- https://bit.ly/3qpE570

Krassilovia: An Amazing Cretaceous Conifer

Reconstructing extinct organisms based on fossils is no simple task. Rarely do paleontologists find complete specimens. More often, reconstructions are based on fragments of individuals found either near one another or at least in similar rock formations. This is especially true for plants as their growth habits frequently result in fragmentary fossilization. As such, fossilized plant remains of a single species are often described as distinct species until subsequent detective work pieces together a more complete picture.

Such was the case for the fossil remains of what were described as Krassilovia mongolica and Podozamites harrisii. Hailing from the Early Cretaceous (some 100-120 million years ago), Krassilovia was only known from oddly spiny cone scales and Podozamites was only known from strap-shaped leaves found in a remote region of Mongolia. Little evidence existed to suggest they belonged to the same plant. That is, until these structures were analyzed using scanning electron micrographs.

(A–C) Articulated seed cones, (D) Isolated cone axis, (E) Incomplete leafy shoot showing a cluster of three attached leaves, (F) Three detached strap-shaped leaves, G) Detail of A showing tightly imbricate interlocking bract-scale complexes, (H) Detail of leaf apex showing converging veins, (I) Three isolated bract-scale complexes showing abaxial (top) and adaxial (bottom) surfaces, (J) Two isolated seeds showing narrow wings. [SOURCE]

These fossilized plant remains were preserved in such detail that microscopic anatomical features such as stomata were visible under magnification. By studying the remains of these plants as well as others, scientists discovered some amazing similarities in the stomata of Krassilovia and Podozamites. Unlike other plant remains associated with those formations, the Krassilovia cone scales and Podozamites leaves shared the exact same stomate morphology. Though not without some uncertainty, the odds that these two associated structures would share this unique morphological trait by chance is slim and suggests that these are indeed parts of the same plant.

The amazing discoveries do not end with stomata either. After countless hours of searching, fully articulated Krassilovia cones were eventually discovered, which finally put the strange spiky cone scales into context. It turns out those spiked scales interlocked with one another, with the two bottom spikes of one scale interlocking with the three top spikes of the scale below it. In life, such interlocking may have helped protect the developing seeds within until they had matured enough to be released. Also, the sheer volume of cone scales coupled with other minute anatomical details I won’t go into here indicate that, similar to Abies and Cedrus cones, Krassilovia cones completely fell apart when fully ripe.

Though not related, the cone scales of the extinct Krassilovia (left) show similarities with the cone scales of modern day Cryptomeria species (right).

Interestingly, the ability to resolve microscopic structures in these fossils has also provided insights into some modern day taxonomic confusion. It turns out that Krassilovia shares many minute anatomical similarities with present day Gnetales. Gnetales really challenge our perception of gymnosperms and their superficial resemblance to angiosperms have led many to suggest that they represent a clade that is sister to flowering plants. However, more recent molecular work has placed the extant members of Gnetales as sister to the pines. Evidence of shared morphological features between extinct conifers like Krassilovia and modern day Gnetales add some interesting support to this hypothesis. Until more concrete evidence is described and analyzed, the true evolutionary relationships among these groups will remain the object of heated debate for the foreseeable fture.

What we can say is that Krassilovia mongolica was one remarkable conifer. Its unique morphology clearly demonstrates that conifers were once far more diverse in form and function than they are currently. Even the habitat in which Krassilovia once lived is not the kind of place you can find thriving conifer communities today. Krassilovia once grew in a swampy habitat. However, whereas only a few extant conifers enjoy swamps, Krassilovia once shared its habitat with a wide variety of conifer species, the likes of which we are only just beginning to appreciate. I for one am extremely excited to see what new fossil discoveries will uncover in the future.

LISTEN TO EPISODE 300 OF THE IN DEFENSE OF PLANTS PODCAST TO LEARN MORE ABOUT THIS FOSSIL AND THE ECOSYSTEM IN WHICH IT ONCE EXISTED.

Photo Credits: [1] [2] [3]

Further Reading: [1]

Fraser Fir: A New Look at an Old Friend

Photo by James St. John licensed under CC BY 2.0

Growing up, Fraser fir (Abies fraseri) was a fairly common sight in our house. Each winter this species would usually win out over other options as the preferred tree for our living room during the holiday season. Indeed, its pleasing shape, lovely color, and soft needles have made it one of the most popular Christmas trees around the world. Amazingly, despite its popularity as a decoration, Fraser fir is so rare in the wild that it is considered an endangered species.

Fraser fir is native to only a handful of areas in the southern Appalachian Mountains. Together with red spruce (Picea rubens), this conifer makes up one of the rarest ecosystems on the continent - the southern Appalachian spruce-fir forest. Such forests only exist at elevations above 4,000 ft (1,200 m) from southwestern Virginia to western North Carolina and eastern Tennessee. The reason for this limited distribution is rooted in both modern day climate and North America’s glacial past.

USGS/Public Domain

Whereas anyone hiking through Appalachian spruce-fir forests could readily draw similarities to boreal forests found farther north, the Appalachian spruce-fir forests are nonetheless unique, hosting many species found nowhere else in the world. Indeed, these forests are holdovers from the Pleistocene when the southeast was much cooler than it is today. As glaciers retreated and the climate warmed, Appalachian spruce-fir forests “retreated” up the mountains, following their preferred climate zones until they hit the peaks of mountains and couldn’t go any further.

Indeed, Fraser fir is in large part limited in its distribution by temperature. This conifer does not perform well at high temperatures and is readily out-competed by other species under warmer conditions. Another factor that has maintained Appalachian spruce-fir forests at elevation is fog. The southern Appalachian Mountains host eastern North America’s only temperate rainforest and fog commonly blankets high elevation areas throughout the year. Research has shown that in addition to keeping these areas cool, fog also serves as an important source of water for Fraser fir and its neighbors. As fog condenses on its needles, these trees are able to absorb that water, keeping them hydrated even when rain is absent.

A view of an Appalachian spruce-fir forest from the Blue Ridge Parkway.

Due to its restricted habitat, Fraser fir has never been extremely common. However, things got even worse as Europeans colonized North America. Over the past two centuries, unsustainable logging and grazing practices have decimated southern Appalachian spruce-fir forests, fragmenting them into even smaller patches with no connectivity in between. In areas where thin, rocky soils were not completely washed away, Fraser fir seedlings did return, however, this was not always the case. In areas where soils were were lost, southern Appalachian spruce–fir forests were incapable of regenerating.

If the story ended there, Fraser fir and its habitat would still be in trouble but sadly, things only got worse with the introduction of the invasive balsam woolly adelgid (Adelges piceae) from Europe around 1900. Like the hemlock woolly adlegid, this invasive, sap-feeding insect has decimated Fraser fir populations throughout southern Appalachia. Having shared no evolutionary history with the adelgid, Fraser fir is essentially defenseless and estimates suggest that upwards of 90% of infect trees have been killed by the invasion. Although plenty of Fraser fir seedlings have sprung up in the wake of this destruction, experts fear that as soon as those trees grow large enough to start forming fissures in their bark, the balsam woolly adelgid will once again experience a massive population boom and repeat the process of destruction again.

Dead Fraser fir as seen from Clingman’s Dome. Photo by Brian Stansberry licensed under CC BY 3.0

The loss of Fraser fir from this imperiled ecosystem has had a ripple effect. Fraser fir is much sturdier than its red spruce neighbors and thus provides an important windbreak, protecting other trees from the powerful gusts that sweep over the mountain tops on a regular basis. With a decline in the Fraser fir canopy, red spruce and other trees are more susceptible to blowdowns. Also, the dense, evergreen canopy of these Appalachian spruce-fir forests produces a unique microclimate that fosters the growth of myriad mosses, liverworts, ferns, and herbs that in turn support species like the endangered endemic spruce-fir moss spider (Microhexura montivaga). As Fraser fir is lost from these areas, the species that it once supported decline as well, placing the whole ecosystem at risk of collapse.

The moss-dominated understory of an Appalachian spruce-fir forest supports species found nowhere else in the world. Photo by Miguel.v licensed under CC BY 3.0

Luckily, the plight of this tree and the habitat it supports has not gone unnoticed by conservationists. Numerous groups and agencies are working on conserving and restoring Fraser fir and southern Appalachian spruce-fir forests to at least a portion of their former glory. This is not an easy task by any means. Aside from lack of funding and human power, southern Appalachian spruce-fir forest conservation and restoration is hindered by the ever present threat of a changing climate. Fears that the life-giving fog that supports this ecosystem may be changing make it difficult to prioritize areas suitable for reforestation. Also, the continued threat from invasive species like the balsam woolly adelgid can hamper even the best restoration and conservation efforts. Still, this doesn’t mean we must give up hope. With continued collaboration and effort, we can still ensure that this unique ecosystem has a chance to persist.

Please visit the Central Appalachian Spruce Restoration Initiative (CASRI) website to learn more!

Photo Credits: [1] [2] [4] [5]

Further Reading: [1] [2] [3] [4]

Insect Egg Killers

© Copyright Walter Baxter and licensed under CC BY-SA 2.0

Plants and herbivores are engaged in an evolutionary arms race hundreds of millions of years in the making. As plants evolve mechanisms to avoid being eaten, herbivores evolve means of overcoming those defenses. Our understanding of these dynamics is vast but largely focused on the actual act of an organism consuming plant tissues. However, there is growing evidence that plants can take action against herbivores before they are even born.

Taking out herbivores before they even have a chance to munch on a plant seems like a pretty effective means of defense. Indeed, for a growing number of plant species, this starts with the ability to detect insect eggs deposited on or in leaves and stems. As Griese and colleagues put it in their 2020 paper, “Every insect egg being detected and killed, is one less herbivorous larva or adult insect feeding on the plant in the near future.” Amazingly, such early detection and destruction has been found in a variety of plant lineages from conifers to monocots and eudicots.

Gumosis in cherries is a form of defense. Photo by Rosser1954/Public Domain

There are a few different ways plants go about destroying the eggs of herbivores. For instance, upon detecting eggs on their leaves, some mustards will begin to produce volatile compounds that attract parasitoid wasps that lay their eggs on or in the herbivore’s eggs. For other plants, killing herbivore eggs involves the production of special egg-killing compounds. Research on cherry trees (Prunus spp.) has shown that as cicadas push their ovipositor into a twig, the damage induces the production of a sticky gum that floods the egg chamber and prevents the eggs from hatching. Similarly, resin ducts full of insect-killing compounds within the rinds of mangoes will rupture when female flies insert their ovipositor, killing any eggs that are deposited within.

One of the coolest and, dare I say, most badass ways of taking out herbivore eggs can be seen in a variety of plants including mustards, beans, potatoes, and even relatives of the milkweeds and involves a bit of sacrifice on the plant end of things. Upon detecting moth or butterfly eggs, leaf cells situated directly beneath the eggs initiate a defense mechanism called the “hypersensitive response.” Though normally induced by pathogenic microbes, the hypersensitive response appears to work quite well at killing off any eggs that are laid.

“Leaves from B. nigra treated with egg wash of different butterfly species and controls inducing or not a HR-like necrosis. Pieris brassicae (P. b.), P. mannii, (P. m.), P. napi (P. n.), and P. rapae (P. r.) and Anthocharis cardamines (A. c.) induce a strong HR-like necrosis. Egg wash of G. rhamni (G. r.) and Colias sp. (C. sp.) induces a very faint response resembling a chlorosis and does not fit into the established scoring system (faintness indicates 1, but showing up on both sides of the leaf indicates 2).” [SOURCE]

Once eggs are detected, a signalling pathway within the leaf ramps up the production of highly reactive molecules called reactive oxygen species. These compounds effectively kill all of the cells upon which the butterfly eggs sit. The death of those plant cells is thought to change the microclimate directly around the eggs, causing them to either dry up or fall off. These forms of plant defense don’t stop once the eggs have been killed either. There is evidence to suggest that the hypersensitive response to insect eggs also induces these plants to begin producing even more anti-feeding compounds, thus protecting the plants from any herbivores that result from any eggs that weren’t killed.

Plants may be sessile but they are certainly not helpless. Defense mechanisms like these just go to show you how good plants can be at protecting themselves. Certainly, the closer we look at interactions like these, the more we will discover about the amazing world of plant defenses.

Photo Credits: [1] [2] [3]

Further Reading: [1] [2]

Dwarf Sumac: North America's Rarest Rhus

James Henderson, Golden Delight Honey, Bugwood.org.

In honor of my conversation with Anacardiaceae specialist, Dr. Susan Pell, I wanted to dedicate some time to looking at a member of this family that is in desperate need of more attention. I would like you to meet the dwarf sumac (Rhus michauxii). Found only in a few scattered locations throughout the Coastal Plain and Piedmont regions of southeastern North America, this small tree is growing increasingly rare.

Dwarf sumac is a small species, with most individuals maxing out around 1 - 3 feet (30.5 – 91 cm) in height. It produces compound fuzzy leaves with wonderfully serrated leaflets. It flowers throughout early and mid-summer, with individuals producing an upright inflorescence that is characteristic of what one might expect from the genus Rhus. Dwarf sumac is dioecious, meaning individual plants produce either male or female flowers. Also, like many of its cousins, dwarf sumac is highly clonal, sending out runners in all directions that grow into clones of the original. The end result of this habit is large populations comprised of a single genetic individual producing only one type of flower.

Current range of dwarf sumac (Rhus michauxii). Green indicates native presence in state, Yellow indicates present in county but rare, and Orange indicates historical occurrence that has since been extirpated. [SOURCE]

Research indicates that the pygmy sumac was likely never wide spread or common throughout its range. Its dependence on specific soil conditions (namely sandy or rocky, basic soils) and just the right amount of disturbance mean it is pretty picky as to where it can thrive. However, humans have pushed this species far beyond natural tolerances. A combination of agriculture, development, and fire sequestration have all but eliminated most of its historical occurrences.

Today, the remaining dwarf sumac populations are few and far between. Its habit of clonal spread complicates matters even more because remaining populations are largely comprised of clonal offshoots of single individuals that are either male or female, making sexual reproduction almost non-existent in most cases. Also, aside from outright destruction, a lack of fire has also been disastrous for the species. Dwarf sumac requires fairly open habitat to thrive and without regular fires, it is readily out-competed by surrounding vegetation.

A female infructescence. Photo by Alan Cressler

Luckily, dwarf sumac has gotten enough attention to earn it protected status as a federally listed endangered species. However, this doesn’t mean all is well in dwarf sumac land. Lack of funding and overall interest in this species means monitoring of existing populations is infrequent and often done on a volunteer basis. At least one study pointed out that some of the few remaining populations have only been monitored once, which means it is anyone’s guess as to their current status or whether they still exist at all. Some studies also indicate that dwarf sumac is capable of hybridizing with related species such as whinged sumac (Rhus copallinum).

Another complicating factor is that some populations occur in some surprisingly rundown places that can make conservation difficult. Because dwarf sumac relies on disturbance to keep competing vegetation at bay, some populations now exist along highway rights-of way, roadsides, and along the edges of artificially maintained clearings. While this is good news for current population numbers, ensuring that these populations are looked after and maintained is a difficult task when interests outside of conservation are involved.

Some of the best work being done to protect this species involves propagation and restoration. Though still limited in its scope and success, out-planting into new location in addition to augmenting existing populations offers hope of at least slowing dwarf sumac decline in the wild. Special attention has been given to planting genetically distinct male and female plants into existing clonal populations in hopes of increasing pollination and seed set. Though it is too early to count these few attempts as true successes, they do offer a glimmer of hope. Other conservation attempts involve protecting what little habitat remains for this species and encouraging better land management via prescribed burns and invasive species removal.

The future for dwarf sumac remains uncertain, but that doesn’t mean all hope is lost. With more attention and research, this species just may be saved from total destruction. The plight of species like the dwarf sumac serve as an important reminder of why both habitat conservation and restoration are so important for slowing biodiversity loss.

Photo Credits: [1] [2] [3]

Further Reading: [1] [2] [3]James Henderson, Golden Delight Honey, Bugwood.org.