Finding The Lobed Spleenwort

This is the story of my first encounter with a hybrid fern back in the spring of 2016.

I love exploring geologically diverse areas. The more rock outcroppings the better. You never know what you are going to find in the numerous nooks and crannies, each with their own unique microclimate. This weekend a few of us decided to get out of town for a bit and explore southern Illinois. You can imagine my excitement then when I laid eyes on a rugged terrain filled with ridges and rock outcrops. With only a few days to botanize, I didn't waste any time. 

The woods were alive with early spring ephemerals. Trilliums, Phacelias, Claytonias, and Dicentras filled the forest with a soft pallet of colors. Along the numerous cliff faces I was finding lots of walking ferns already awaking from the mild winter. At one point I found myself following the meandering path of a small stream. Along each side were small cliffs that were carved out of the surrounding bedrock over eons. Their appearance was softened by the myriad species of lichen and moss that carpeted their surfaces. Upon this moss, small ferns and plants are able to take root. My eye kept leaving the creek bed, finding its way along the rocks, looking for anything peculiar that might catch my eye. That's when I saw it. 

Sticking out of a small hole in the rock was an interesting looking fern. At first glance I thought it was another walking fern. Something was off though. It's outline didn't look right and I had to investigate. Its fronds looked lobed. Indeed they were. This was no walking fern but I wasn't ready to jump to conclusions just yet. I pulled out my fern guide in order to confirm my suspicions. 

What I was looking at was a hybrid. Not just any hybrid either. This unique looking little plant is known scientifically as Asplenium pinnatifidum - the lobed spleenwort. I was just lucky enough to be botanizing on the far western portion of its range. Although it is far more prevalent in the Appalachian Mountains, this hybrid is by no means common. I was very lucky to have spotted it.

It is the result of a chance mix between the walking fern (Asplenium rhizophyllum) and the mountain spleenwort (Asplenium montanum). My original inclination towards walking fern wasn't far off. One interesting aspect of this particular hybrids biology is that it is an allotetraploid. Instead of getting one set of chromosomes from each parent (diploid), this little fern gets a full compliment of chromosomes from each, giving it 4 copies total. 

Because it has a lot of functional chromosomes to work with, the lobed spleenwort is fertile. As such, experts have given it the designation of a true species. It can even go on to produce subsequent hybrids. It has been reported to hybridize with other members of the genus Asplenium, however, the offspring produced from these crosses are usually sterile. 

I looked around the area to see if I could find more. In total I only saw two. That's not to say more aren't out there. There are plenty of rock ledges and cliffs that make this region so uniquely beautiful. It is likely that this hybrid fern has unknown populations growing out of reach of watchful eyes. Long may it be that way. 

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

The Truth About Coffee

Photo by Ria Tan licensed under CC BY-NC-ND 2.0

Mmm mmm coffee. This wonderful elixir has taken over the world. Though individual tastes and preferences vary, there is no denying that most folks who turn to coffee enjoy its effects as a stimulant. Many an In Defense of Plants post has been written in a coffee-fueled frenzy. Even as I write this piece, I am taking breaks to sip on a warm mug of the stuff. Coffee has plenty of proponents as well as its fair share of nay sayers but the health effects don't really concern me much. Today I would rather talk with you about the shrubs that are behind all of this. 

The coffee we drink comes from a handful of shrubs in the genus Coffea. Native to parts of Africa, these shrubs are distant relatives of plants like buttonbush (Cephalanthus occidentalis) and the bedstraws (Galium sp.). The "beans" that we brew coffee from are not beans at all but rather a type of pit or stone found in the center of a bright red berry. Before they are roasted, the "beans" are actually green. Plants in this genus produce an alkaloid compound known as caffeine. Though it may seem strange, the purpose of caffeine is not to stimulate the human nervous system (though it is a wonderful side effect) but rather it is produced as a defense mechanism for the plant. Making this compound is a complex process that involves many metabolic steps within the tissues of the plant. There are certain factions out there who would like to argue that this is proof against evolution but, as always, evidence seems to be the downfall of their argument. 

Creationists will tell you that the adaptations we see throughout the living world are too complex to have happened by accident. In reality, there is a vast amount of evidence that disputes this. Caffeine is one such example. It has evolved independently multiple times in many different plant lineages. Looking at the genome of coffee, researchers at the University at Buffalo (my alma mater) found that the genes involved in the synthesis of caffeine did not arise all at once. Instead, the genes duplicated multiple times throughout the history of this genus with each duplication coding for another step in the process of producing the caffeine molecule. The interesting part is that each step of this evolutionary process produced a chemical that was itself useful to the plant. The precursor compounds are bitter and toxic to the kinds of animals that like to nibble on the plant. 

As it turns out, the benefits that the plants get from caffeine aren't restricted to defense either. Coffee, as well as other flowering plants such as citrus, produce small amounts of caffeine in their nectar. Researchers at Arizona State University found that bees were 3 times more likely to remember a flowers scent when there was caffeine in the nectar than if there wasn't. This serves a great benefit to the plant producing it because it means that its flowers are much more likely to get pollinated. As it turns out, humans aren't the only species that enjoys a good buzz from caffeine.

Before we get too excited over coffee, we must remember that is definitely has its downside. Worldwide, we humans drink roughly 2.25 billion cups of the stuff every day. In order to produce that much coffee, humans have turned somewhere around 11 million hectares of land into coffee plantations. This has come at an extreme cost to the environment. Also, being a tropical species, the types of habitat used to grow coffee were once lush, tropical rain forests. A majority of coffee consumed around the world is produced in monocultures. Where there once stood towering trees and a lush understory is now an open, chemically-laden field of coffee shrubs. There is hope, however, and it is rising in popularity. 

If you enjoy coffee as much as I do, you should certainly consider switching over to shade grown coffee. I have attached a fair amount of literature at the bottom of this post but the long story short of it is that growing coffee is much less harmful to the environment when it is grown in a forest rather than open plantations. The structural complexity of shade grown coffee farms allows a greater diversity of plant and animal species to coexist with one another. Species diversity and richness are significantly higher on shade grown farms than on open field plantations. 

So, there you have it. Coffee is as complex as it is interesting. We humans are simply lucky to have stumbled across a plant that interacts with our brain chemistry in wonderful ways. Certainly coffee has benefitted in the long run. 

Photo Credit: Ria Tan (http://bit.ly/1pFQD1J)

Further Reading:
http://www.sciencemag.org/content/345/6201/1181.full

https://asunews.asu.edu/20130307_beesandcaffeine

http://s.si.edu/1o6wOaj

http://www.sciencedaily.com/releases/2012/08/120807101357.htm

http://bit.ly/1S6dLVV

Pasqueflower

Photo by Jerzy Strzelecki licensed under CC BY-SA 3.0

The true harbinger of spring on the northern prairies of North America, Europe, China and Russia is none other than the pasqueflower (Anemone patens). It bursts forth from the ground with its fuzzy, dissected leaves often before all of the snow has had a chance to melt. It then proceeds to put on quite a show with flowers that range the spectrum from white to deep purple. Everything about this plant is adapted to take advantage of early spring before competing vegetation gets the upper hand. 

One of the coolest aspects of pasqueflower life are its flowers. These parabolic beauties need to be able to function despite the constant risk of freezing temperatures. To stay warm, the flowers will actually track the sun's movement across the sky. In this way, they are able to absorb solar radiation all day. What's more, the parabolic shape and reflective surface of the petals serves to bounce solar radiation towards the center, thus amplifying the amount of heat. Pasqueflower blooms can actually maintain a daytime flower temperature upwards of 18 degrees Celsius above ambient temperatures, not only providing a warm spot for pollinators but also increasing the rate at which the seeds develop. 

Photo by Otro13 licensed under CC BY-SA 3.0

The seeds themselves are quite interesting structures as well. Getting into the soil can be a difficult task when your neighbors are thick prairie grasses. Pasqueflowers get around this problem by producing seeds that literally bury themselves. Each seed is attached to an awn that is made up of alternating strands of tissue. Each strand varies in its ability to absorb moisture. As spring rains come and go, the awns will twist and turn with the resulting effect of drilling the seeds directly into the ground. 

Once the surrounding vegetation begins to wake up, pasqueflower is already getting ready to go dormant. By mid-July it is usually back underground. It is a prime example of how breaking dormancy early can help a plant beat the competition of the growing season. Also, pasqueflower can be very long lived, with individuals persisting upwards of 50 years in a given location. Not only is this plant is both hardy and beautiful, it also has the added ecological benefit of providing early prairie pollinators with a much needed boost of energy. 

Photo Credit: [1] [2]

Further Reading: [1] [2]
 

Of Gunnera and Cyanobacteria

Photo by UnconventionalEmma licensed under CC BY-NC 2.0

Nitrogen is a limiting resource for plants. It is essential for life functions and yet they do not produce it on their own. Instead, plants need to get it from their environment. They cannot uptake gaseous nitrogen, which is a shame because it makes up 78.09% of our atmosphere. As such, some plants have developed very interesting ways of obtaining nitrogen from their environment. Some, like the legumes, produce special nodules on their roots, which house bacteria that fix atmospheric nitrogen. Other plants utilize certain species of mycorrhizal fungi. One family of plants, however, has evolved a symbiotic relationship that is unlike any other in the angiosperm world.

A Gunnera inflorescence. Photo by Lotus Johnson licensed under CC BY-NC 2.0

Meet the Gunneras. This genus has a family all to itself - Gunneraceae. They can be found in many tropical regions from South America to Africa and New Zealand. Some species of Gunnera are small while others, like Gunnera manicata, have leaves that can be upwards of 6 feet in diameter. Their leaves are well armed with spikes and spines. All in all they are rather prehistoric looking. The real interesting thing about the Gunneras though, is in the symbiotic relationship they have formed with cyanobacteria in the genus Nostoc.

Traverse section of a Gunnera stem showing cyanobacteria colonies (C) and the cup-like structures (S) where they enter the stem. [SOURCE]

Gunnera produce cuo-like glands that house these cyanobacteria. The glands are filled with a special mucilage that not only attracts the cyanobacteria, but also stimulates it to grow. Once inside the glands, the cyanobacteria begins to grow into the plant, eventually fusing with the Gunnera cells. From there the cyanobacteria earn their keep by producing copious amounts of usable nitrogen and in return, the Gunnera supplies carbohydrates. This relationship is amazing and quite complex. It also offers researchers an insight into how such symbiotic relationships evolve.

Photo Credit: [1] [2] [3]

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

Velvet Turtleback

Photo by Stan Shebs licensed under CC BY-SA 3.0

Death valley doesn't seem like a place where life would thrive. Nonetheless, a unique assemblage of plants can be found living in this hostile environment. These plants are well adapted to take advantage of those fleeting moments when things aren't so bad. A flush of flowers following a rare desert downpour is a reminder that even the harshest environments on this planet can harbor rich biodiversity. One of the coolest plants found in Death valley has to be the velvet turtleback (Psathyrotes ramosissima).

This peculiar little aster forms fuzzy little cushions that superficially resemble the domed shell of a turtle. The tightly packed leaves even give the appearance of scales. Everything about this plant is adapted to life in one of the driest places on Earth. For starters, it is a desert annual. Its seeds can lie dormant in the soil for many years until the perfect conditions arise. Once that happens, growth can be surprisingly rapid. In Death Valley, good conditions don't last long.

Photo by Dawn Endico from Menlo Park, California - Turtleback Uploaded by PDTillman licensed under CC BY-SA 2.0

Even when conditions are right, its desert environment can still be quite challenging. Water loss and sun scorch are constant threats. Its cushion-like growth form and fuzzy leaves help reduce water loss as hot, dry winds whip across the region. The fuzzy leaves also help to reflect punishing UV rays that may otherwise fry the sensitive photosynthetic machinery inside.

All in all this is an incredible little plant. It survives in one of the toughest environments on the planet through a combination of timing and physiology. It is also but one of many desert-adapted species painting the valley during the brief growing season. As is typical of most of the plants of this region, its beauty is ephemeral and won't last much longer and to me, that makes it all the more wonderful.

Photo Credits: Stan Shebs and Dawn Endico - Wikimedia Commons

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

An Underground Orchid

Photo by Jean and Fred licensed under CC BY 2.0

Are you ready to have your mind blown away? What you are looking at here is not some strange kind of mushroom, though fungus is involved. What you are seeing is actually the inflorescence of a parasitic orchid from Australia that lives and blooms underground!

Meet Rhizanthella gardneri. This strange little orchid is endemic to Western Australia and it lives, blooms, and sets seed entirely underground. It is extremely rare, with only 6 known populations. Fewer than 50 mature plants are known to exist. This is another one of those tricky orchids that does not photosynthesize but, instead, parasitizes a fungus that is mycorrhizal with the broom honey myrtle (Melaleuca uncinata). To date, the orchid has only been found under that specific species of shrub. Because of its incredibly unique requirements, its limited range, and habitat destruction, R. gardneri is critically endangered.

The flowers open up a few centimeters under the soil. They are quite fragrant and it is believed that ants, termites, and beetles are the main pollinators. The resulting seeds take up to 6 months to mature and are quite fleshy. It is hypothesized that some sort of small marsupial eats them and consequently distributes them in its droppings. Either way, the chances of successful sexual reproduction for this species are quite low. Because of this, R. gardneri also reproduces asexually by budding off daughter plants.

Despite not photosynthesizing, this orchid is quite unique in that it still retains chloroplasts in its cells. They are a very stripped down form of chloroplast though, containing about half of the genes a normal chloroplast would. It is the smallest known chloroplast genome on the planet. This offers researchers a unique opportunity to look deeper into how these intracellular relationships function. The remaining chloroplast genes code for 4 essential plant proteins, meaning chloroplasts offer functions beyond just photosynthesis.

I am so amazed by this species. I'm having a hard time keeping my jaw off the ground. What an amazing world we live in. If you would like to see more pictures of R. gardneri, please make sure to check out the following website:
http://www.arkive.org/underground-orchid/rhizanthella-gardneri/

Photo Credit: Jean and Fred Hort

Further Reading:
http://www.sciencedaily.com/releases/2011/02/110208101337.htm

http://www.eurekalert.org/pub_releases/2011-02/uowa-wai020711.php

http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=20109

Studying Mimicry in Orchids Using 3D Printing

Photo by Luis Baquero licensed under CC BY-NC-ND 2.0

Just when I thought I could stop acting surprised by the myriad applications of 3D printing, a recent study published in the journal New Phytologist has me pulling my jaw up off the floor. Using a 3D printer, researchers from the University of Oregon have unlocked the mystery surrounding one of the more peculiar forms of mimicry in the botanical world. 

The genus Dracula is probably most famous for containing the monkey face orchids (Dracula simia). Thanks to our predisposition for pareidolia, we look at these flowers and see a simian face staring back at us. Less obvious, however, is the intricate detail of the labellum, which superficially resembles the monkey's mouth. A close inspection of this highly modified petal would reveal a striking resemblance to some sort of gilled mushroom. 

Indeed, a mushroom is exactly what the Dracula orchids are actually trying to mimic. The main pollinators of this genus are tiny fruit flies that are mushroom specialists. They can be seen in the wild crawling all over Dracula flowers looking for a fungal meal and a place to mate. Some of the flies inevitably come away from the Dracula flower with a wad of pollen stuck to their backs. With any luck they will fall for the ruse of another Dracula flower and thus pollination is achieved. 

Despite being well aware of this mimicry, scientists didn't quite know what specifically attracted the flies to the flower. This is where the 3D printer came in. The research team made exact replicas of the flowers of Dracula lafleurii out of odorless silicone. They also printed individual flower parts. In doing so, the researchers were able to vary the color patterns as well as the scent of each flower. Using the parts, they were also able to construct chimeras, which allowed them disentangle which parts contribute most to the mimicry. 

What they discovered is that the key to Dracula's mushroom mimicry lies in its gilled labellum. This petal not only looks like a mushroom, it smells like one too. The result is a rather ingenious ruse that its tiny fly pollinators simply can't resist. What's more, this approach offers an ingenious way of investigating the evolution of mimicry throughout the botanical kingdom. 

Photo Credit: Luis Baquero (http://bit.ly/21GhYGJ)

Further Reading:
http://onlinelibrary.wiley.com/doi/10.1111/nph.13855/abstract

Plant Plasticity

One of the central tenets of evolutionary science is that individuals within a species vary, however slightly, in their form, physiology, and behavior. Without variability, life would languish, remaining static in a soupy ooze somewhere in the oceans. Perhaps it may not have evolved in the first place. Regardless, observation and experimentation has taught us a lot about how variation among individuals or populations can drive evolution. Today I would like to introduce you to a tiny plant native to northern and western North America that is teaching us a lot about how mating systems develop in plants.

Meet Collinsia parviflora, the maiden blue eyed Mary. Few plants are as iconic to my time living out west than this wonderful little plant. Indeed, C. parviflora is highly variable. It ranges in size from 5 for 40 centimeters in height and produces lovely little flowers that range from 4 to 7 millimeters in length. The size range of these flowers is key to investigating variations in pollination strategies. 

C. parviflora has evolved what researchers refer to as a mixed mating strategy. Populations differ in that some plants self pollinate whereas others fully outcross with the help of a variety of bees. Exactly why these plants would maintain both strategies can tell us a lot about how mating systems develop in plants. What researchers have found is that there seems to be a tradeoff. 

Populations that frequently self are often located in the harshest environments. Cold temperatures and a short growing season make investing in complex floral development a risky strategy. Indeed, plants growing where environmental conditions are harshest produce smaller flowers. These small flowers pack all of their reproductive bits close together, thus increasing the chances of self fertilization. It has been found that despite the risk of inbreeding, these plants produce far more seeds than plants that produce larger flowers and experience high rates of insect pollination. 

The reasons for this are quite complex and more work is needed to be certain but it would seem that this is all an evolutionary adaptation to dealing with varied climates. With wide ranging species like C. parviflora, populations can experience highly varied environmental conditions. It would seem maladaptive to focus in on one particular reproductive strategy. As such, C. parviflora has evolved a range of possible anatomies as a way of adapting to many unique local conditions. If times are good and pollinators are abundant, it makes more sense to hedge bets on sexual reproduction whereas when conditions are poor and pollinators are scarce, it makes sense to produce offspring with a genome identical to that of the parents. If they can exist in a harsh location then so can the cloned offspring. 

Investigations into the mating system of this tiny plant has revealed that big things can really come in small packages. I miss seeing this species. Its amazing how these tiny little flowers can be so numerous as to turn wide swaths of its habitat a pleasing shade of blue. 

Further Reading:
http://www.amjbot.org/content/90/6/888.full

http://plants.usda.gov/core/profile?symbol=COPA3

Rhizanthes lowii

Photo Credit: Ch'ien C. Lee - www.wildborneo.com.my/photo.php?f=cld1500900.jpg

Imagine hiking through the forests of Borneo and coming across this strange object. It's hairy, it's fleshy, and it smells awful. With no vegetative bits lying around, you may jump to the conclusion that this was some sort of fungus. You would be wrong. What you are looking at is the flower of a strange parasitic plant known as Rhizanthes lowii.

Rhizanthes lowii is a holoparasite. It produces no photosynthetic tissues whatsoever. In fact, aside from its bizarre flowers, its doesn't produce anything that would readily characterize it as a plant. In lieu of stems, leaves, and roots, this species lives as a network of mycelium-like cells inside the roots of their vine hosts. Only when it comes time to flower will you ever encounter this species (or any of its relatives for that matter).

The flowers are interesting structures. Their sole function, of course, is to attract their pollinators, which in this case are carrion flies. As one would imagine, the flowers add to their already meaty appearance a smell that has been likened to that of a rotting corpse. Even more peculiar, however, is the fact that these flowers produce their own heat. Using a unique metabolic pathway, the flower temperature can rise as much as 7 degrees above ambient. Even more strange is the fact that the flowers seem to be able to regulate this temperature. Instead of a dramatic spike followed by a gradual decrease in temperature, the flowers of R. lowii are able to maintain this temperature gradient throughout the flowering period.

Photo Credit: Ch'ien C. Lee - www.wildborneo.com.my/photo.php?f=cld1500900.jpg

There could be many reasons for doing this. Heat could enhance the rate of floral development. This is a likely possibility as temperature increases have been recorded during bud development. It could also be used as a way of enticing pollinators, which can use the flower to warm up. This seems unlikely given its tropical habitat. Another possibility is that it helps disperse its odor by volatilizing the smelly compounds. In a similar vein, it may improve the carrion mimicry. Certainly this may play a role, however, flies don't seem to have an issue finding carrion that has cooled to ambient temperature. Finally, it has also been suggested that the heat may improve fertilization rates. This also seems quite likely as thermoregulation has been shown to continue after the flowers have withered away.

Regardless of its true purpose, the combination of lifestyle, appearance, and heat producing properties of this species makes for a bizarrely spectacular floral encounter. To see this plant in the wild would be a truly special event.

Photo Credit: Ch'ien C. Lee - www.wildborneo.com.my/photo.php?f=cld1500900.jpg

Further Reading: [1] [2]

A Litter Trapping Orchid From Borneo

Ch'ien C. Lee - http://www.wildborneo.com.my/

Epiphytes live a unique lifestyle that can be quite challenging. Sure, they have a relatively sturdy place on a limb or a trunk, however, blistering sun, intense heat, and plenty of wind can create hostile conditions for life. One of the hardest things to come by in the canopy is a steady source of nutrients. Whereas plants growing in the ground have soil, epiphytes must make do with whatever falls their way. Some plants have evolve a morphology that traps falling litter. There are seemingly endless litter trapping plants out there but today I want to highlight one in particular.

Meet Bulbophyllum beccarii. This beautiful orchid is endemic to lowland areas of Sarawak, Borneo. What is most interesting about this species is how it grows. Instead of forming a clump of pseudobulbs on a branch or trunk, this orchid grows upwards, wrapping around the trunk like a leafy green snake. At regular intervals it produces tiny egg-shapes pseudobulbs which give rise to rather large, cup-shaped leaves. These leaves are the secret to this orchids success.

The cup-like appearance of the leaves is indeed functional. Each one acts like, well, a cup. As leaves and other debris fall from the canopy above, the orchid is able to capture them. Over time, a community of fungi and microbes decompose the debris, turning it into a nutrient-rich humus. Instead of having to compete for soil nutrients like terrestrial species, this orchid makes its own soil buffet!

If that wasn't strange enough, the flowers of this species are another story entirely. Every so often when conditions are just right, the plant produces an inflorescence packed full of hundreds of tiny flowers. The flowers dangle down below the leaves and emit an odor that has been compared to that of rotting fish. Though certainly disdainful to our sensibilities, it is not us this plant is trying to attract. Carrion flies are the main pollinators of this orchid and the scent coupled with their carrion-like crimson color attracts them in swarms.

The flies are looking for food and a place to lay their eggs. This is all a ruse, of course. Instead, they end up visiting a flower with no rewards whatsoever. Regardless, some of these flies will end up picking up and dropping off pollinia, thus helping this orchid achieve pollination.

Epiphyte diversity is incredible and makes up a sizable chunk of overall biodiversity in tropical forests. The myriad ways that epiphytic plants have adapted to life in the canopy is staggering. Bulbophyllum beccarii is but one player in this fascinating niche.

Photo Credits:
Ch'ien C. Lee - http://www.wildborneo.com.my/

Further Reading:
http://www.orchidspecies.com/bulbbeccarrii.htm

Bowerbirds - Accidental Gardeners

To look upon the bower of a male bowerbird is to see something bizarrely familiar. These are not elaborate nests but rather architectural monuments whose sole purpose is to serve as a staging ground for mating displays. Males build and adorn these structures with precision and a sense of aesthetics. Because of this behavior, at least one species of bowerbird, the spotted bowerbird, can add another occupation to its resume - accidental gardener.

Photo by Jess Isden via University of Exeter

When a male finds a certain color he likes, he scours the landscape in search of these treasures. For many male bowerbirds, fruits offer a wide array of colors and textures of which they can add to their menagerie. Male spotted bowerbirds seem to have a fondness for the fruits of the potato bush (Solanum ellipticum). Their stark green hue contrasts nicely with the bower architecture.

When the fruits start to decompose, they no longer serve any purpose for the male bowerbird and he tosses them aside. Seeds begin to accumulate around the bower and after some time they will germinate. Researchers decided to investigate this relationship a bit further. What they found was pretty astounding.

They discovered that bush potato plants grew in higher numbers around bowers than they do at random locations throughout the forest. What's more, the fruits produced by bush potatoes growing near bowers were much greener than those of plants elsewhere. In effect, male spotted bowerbirds are not only cultivating the bush potato, they are also artificially selecting for improved coloration of its fruits.

To date, this is the only example of something other than a human cultivating a plant for reasons other than food. The similarities between human cultivation and bowerbird cultivation are mind blowing. Similar to human farmers, male bowerbirds clear the site of competing vegetation and remove the fuel load so as to minimize the risk of fire, all of which provides ideal habitat for germination. Though the male bowerbirds are not intentionally cultivating the bush potato, they have nonetheless entered into a mutualistic relationship in which the males get ready access to beautiful fruits and in return, the bush potato gets a nice, safe place to grow.

Photo Credit: University of Exeter

Further Reading:

http://www.sciencedirect.com/science/article/pii/S0960982212002084

A Flower Trapped in Amber

Photo by George Poinar [SOURCE]

Thanks to a 30 year old collection of amber tucked away in the drawers of a museum, we now have the first fossil record of the asterid lineage. Discovered in the Dominican Republic back in 1986, this particular chunk of amber contains a tiny flower about a centimeter in length. The preservation is astounding, allowing researchers to accurately identify this as a member of the genus Strychnos.

The asterid lineage contains many orders that we would be familiar with including Gentianales, Lamiales and Solanales. It is highly derived yet poorly represented in the fossil record. Because of the challenges associated with accurately dating amber, scientists estimate that this flower is somewhere between 15 - 45 million years old. To put this in perspective, North and South America were not even connected at this point in time. What's more, the details preserved in these amber deposits are allowing researchers to piece together what the forest in this region would have looked like.

These fossils show that this forest "contained a distinct canopy layer composed of legumes such as algarroba (Hymenaea protera), cativo (Prioria spp.) and nazareno (Peltogyne spp.), with emergent trees like caoba (Swietenia; Meliaceae) extending through the canopy. The subcanopy and understory were represented by royal palms (Roystonea) and figs (Ficus; Moraceae). The shrub layer included other types of palms as well as acacias. Grasses like pega-lega (Pharus) and bambusoids (Alarista) colonized the forest floor. Orchids, bromeliads, ferns and vines covered the trees, and various lianas were also part of this tropical forest."

Pretty amazing for bits and pieces of solidified tree sap. This particular flower has been named Strychnos electri, a now extinct species. However, the morphological characteristics show that this particular genus as well as the asterid lineage were already well established at this time. Discoveries such as this are offering highly detailed windows into the past, which allows us to better understand flowering plant evolution and ecosystem change.

Photo Credit: George Poinar

Further Reading:
http://www.nature.com/articles/nplants20165

Anise: An Angiosperm Success Story

Illicium floridanum Photo by Scott Zona licensed under CC BY-NC 2.0

I must admit there are few flavors I loath more than anise (and consequently licorice and fennel). Regardless of the flavor, I nonetheless find myself enamored by their whorled seed capsules of star anise. In an attempt to reconcile my feelings towards anise in a culinary sense, I decided to get to know the plants that are responsible for it and I am so glad that I did. As it turns out, this group of small trees and shrubs offer us a glimpse at some of the earliest branchings on the angiosperm family tree.

We get star anise from the genus Illicium. Native to humid tropical understories, there are roughly 40 species scattered around southeast Asia, southeastern North America, the Caribbean, and parts of Mexico. Molecular as well as fossil evidence suggests this group diverged during the mid to late Cretaceous, not long after flowering plants came onto the scene. Indeed, along with Amborella and Nymphaeales, Illicium represent the three lineages that are sister to all other flowering plants alive today.

Illicium henryi Photo by Scott Zona licensed under CC BY-NC 2.0

To call them primitive, however, would be a serious misnomer. Because they diverged so early on, these lineages represent serious success stories in flowering plant evolution. Instead, think of them as fruitful early experiments in angiosperm evolution. Illicium has characteristics that set it out as being sister to all other flowering plants. For instance, the vascular tissues more closely resemble those of gymnosperms than they do angiosperms. Also, like the other sister angiosperms, Illicium blur the line between the long standing categories of monocot and eudicot. As such, they are sometimes referred to as "paleoherbs." Another key diagnostic feature lies in their floral morphology.

They don't have what could be considered true petals or sepals. Instead, they have whorls of tepals, which start off sepal-like and gradually become more petal-like as you near the center of the flower. The stamens, which are laminar or leaf-like, are also arranged in a dense whorl surrounding a yet another whorl of fused carpels. Once fertilized, each carpel gives rise to a hard, glossy seed. As the carpels mature and begin to dry, the individual capsules get tighter and tighter until at some point the seed is pinched so hard that it is ejected from a slit in the fruit in projectile fashion.

Illicium verum. Photo by Tim Waters licensed under CC BY-NC-ND 2.0

Although this research will never rectify the taste of this spice, it nonetheless has given me a new found respect and sense of awe for this genus. To look upon the fruit of Illicium is to look at a biological structure that has stood the test of time. These plants are evolutionary successes that should be admired for their unique place in the story of flowering plant evolution.

Photo Credits: Scott Zona and Tim Waters

Further Reading: [1]

The Evolution of Bulbs

Photo by Ewan Bellamy licensed under CC BY-NC-ND 2.0

Spring time is bulb time. As the winter gives way to warmer, longer days, bulbs are among the first of our beloved botanical neighbors to begin their race for the sun. Functionally speaking, bulbs are storage organs. They are made up of a short stem surrounded by layers of fleshy leaves, which contain plenty of energy to fuel rapid growth. Their ability to maintain dormancy is something most of us will be familiar with.

As you might expect, bulbs are an adaptation for short growing seasons. Their ability to rapidly grow shoots gives them an advantage during short periods of time when favorable growing conditions arrive. Despite the energetic costs associated with supplying and maintaining such a relatively large storage organ, the ability to rapidly deploy leaves when conditions become favorable is very advantageous.

Contrast this with rhizomatous species, which are often associated with a life in the understory (though not exclusively) or in crowded habitats like grasslands where competition for light and space can be fierce. Their ambling subterranean habit allows them to vegetatively "explore" for light and nutrients. What's more, the connected rhizomes allow the parent plant to provide nutrients to the developing clones until they grow large enough to support themselves. Under such conditions, bulbs would be at a disadvantage.

Bulbs have evolved independently throughout the angiosperm tree. Many instances of a switch from rhizomatous to bulbous growth habit occurred during the Miocene (23.03 to 5.332 million years ago) and has been associated with a global decrease in temperature and an increase in seasonality at higher latitudes. The decrease in growing season may have favored the evolution of bulbous plants such as those in the lily family. Today, we take advantage of this hardy habit, making bulbous species some of the most common plants used in gardens.


Further Reading: [1]
 

<3 The Heart <3

Have you ever wondered why the heart symbol is equated with love? After all, it bears no physical resemblance to an actual human heart. There have been many explanations put forth regarding this association, mostly dealing with parts of the female anatomy, but one hypothesis is quite intriguing and, if anything else, makes for a pretty great tale.

It all starts with the Romans. They were known for a plethora of accomplishments and advancements in technology as well as some serious tribalism, but one thing is for certain, they were an amorous lot! The Romans enjoyed love making and indeed were some of the first people to use certain forms of contraceptives. There was one method of birth control that the Romans really seemed to prefer - silphium.

We aren’t really sure what exactly silphium was but what we do know is that it is most likely a close relative of fennel. This puts it in the carrot family. The reason we don’t know what it was for certain is because it is believed to be extinct. The Romans quite literally fornicated it out of existence. Because it is no longer extant, we cannot speak to the efficacy of its contraceptive properties but the Romans sure believed in it. It became so popular that it was worth its weight in silver. The thing that made it so coveted was that it didn’t seem to be able to grow anywhere but a narrow swath of land along the Mediterranean Sea. It was so rare and so highly sought after that poaching was a regular theme. On top of that, cattle that grazed on it were said to have delectably flavored meat. These factors coupled with desertification of its habitat were too much for a plant with such a narrow range. It was pushed over the edge into the bottomless pit of extinction. 

So, what does this plant have to do with the heart symbol? By examining Roman illustrations of the plant it was discovered that the seeds were heart shaped. They believe the Romans began to associate the shape of the seed with the ability to have lots of sex without the risk of child birth. It became such a powerful symbol that they even went as far as to stamp it on their currency (pictured here). Whether or not all of these facts represent the true story is up for a lot of debate. I am, after all, no historian. What can’t be denied is the popularity of silphium during this period in Roman history. Think about that the next time a relative sends you a heart shaped Valentines Day card!

Ferula tingitana is believed to be the closest extant relative of silphium. Photo by Ruben0568 licensed under CC BY-SA 4.0

Photo Credit: Expedition magazine Vol. 34, Nos. 1-2, 1992 om p. 62 and Ruben0568 (Wikimedia Commons)

Further Reading:
http://io9.com/5923071/did-the-romans-drive-a-birth+control-plant-to-extinction

http://www.damninteresting.com/the-birth-control-of-yesteryear/

Screw Pines, Volcanism, and Diamonds

Photo by Jakob Fahr/iNaturalist (CC BY-NC)

The association between geology and botany has always fascinated me. The closer you look, the more you can't separate the two. Rocks and minerals influence soil characteristics, which in turn influences which plant species will grow and where, which in turn influences soil properties. Take for instance the case of kimberlite.

Kimberlite is a volcanic rock whose origin is quite intense. Kimberlite is found in the form of large vertical columns, often referred to as pipes. They are the result of some seriously explosive volcanism. Intense heat and pressure builds deep within the mantle until it explodes upward, forming a column of this igneous rock. 

Over long spans of time, these pipes begin to weather and erode. This results in soil that is rich in minerals like magnesium, potassium, and phosphorous. As anyone who gardens can tell you, these are the ingredients of many fertilizers. In Africa where these sorts of pipes are well known, there is a species of plant that seems to take advantage of these conditions. 

It has been coined Pandanus candelabrum and it belongs to a group of plants called the screw pines. They aren't true pines but are instead a type of angiosperm. Now, the taxonomy of the genus Pandanus is a bit shaky. Systematics within the family as a whole has largely been based on fragmentary materials such as fruits and flowers. What's more, for much of its taxonomic history, each new collection was largely regarded as a new species. You might be asking why this is important. The answer has something to do with the kimberlite P. candelabrum grows upon. 

There is something other than explosive volcanic activity that makes kimberlite famous. It is mostly known for containing diamonds. In a 2015 paper, geologist Stephen E. Haggerty made this connection between P. candelabrum and kimberlite. As far as anyone can tell, the plant is a specialist on this soil type. As such, prospectors are now using the presence of this plant as a sort of litmus test for finding diamond deposits. This is why I think taxonomy becomes important. 

If P. candelabrum turns out not to be a unique species but rather a variation then perhaps this discovery doesn't mean much for the genus as a whole. However, if it turns out that P. candelabrum is a truly unique species then this new-found association with diamond-rich rocks may spell disaster. Mining for diamonds is a destructive process and if every population of P. candelabrum signals the potential for diamonds, then the future of this species lies in the balance of how much our species loves clear, shiny chunks of carbon. A bit unsettling if you ask me. 


Further Reading:
http://econgeol.geoscienceworld.org/content/110/4/851.full

Why Trees Have Rings (and why they are so useful)

Dendrochronology is a field of study that focuses on tree rings. Though it may not be obvious, the amount of information we gain from looking at these rings is astounding. This research goes far deeper than simply finding out how old a tree was when it died. Dendrochronological data can be used to investigate paleoclimates, paleoecologies, and the archaeological dating of buildings and artwork. It is amazing how a practiced eye can look back in time. To date, we have an unbroken dendrochronological record for the northern hemisphere dating back some 12,000+ years!

All of this would not be possible if it were not for tree rings. But what exactly are they and how do they form? The answer is physiological. Essentially tree rings result from patterns in vascular tissues. Early in the spring, before the leaves start to grow, a layer of tissue just under the bark called the cambium begins to divide. In this cool, water-laden time of the growing season the vessels that are produced are large and less dense. This is the beginning of the spring or early wood. Although they are not as strong as vessels that are produced later in the season, they sure can move a lot of water. Things are a bit different for conifers. Because they do not produce vessel elements in their wood, this large cell growth is initiated instead by large amounts of a growth hormone called auxin that is produced by the new buds. This causes the cells of the early wood in conifers to grow large in a similar way to that of the hardwoods. 

As summer heats up, things start to change. The cambium starts producing smaller, thicker cells. The vessels that result from this are much stronger than those of the early wood. This late wood as it is called gives trees much of their rigidity and strength. Late wood is also resistant to what is called cavitation, a process in which water within the tree can literally vaporize, causing a damaging embolism during the hottest months of summer. In conifers, bud growth stops by mid to late summer and with it much of the production of auxin. This results in smaller vessels as well. 

In temperate regions, this cycle of growth occurs over the course of a growing season. As such, each ring demarcates a year in that trees life. Because so much of a trees growth is determined by environmental conditions, the size and shape of the rings can tell a lot about the conditions in which that tree was growing. That is why dendrochronology is such a useful tool. By looking at tree rings from all over the world, researchers can tell what was going on at that point in time. And, though it was long thought that this was a phenomenon restricted to seasonal forests, we are finding that even some tropical trees produce annual growth rings. This is especially true in regions that have a measurable dry season. It just goes to show you that data comes in many shapes, sizes, and forms.

LEARN MORE ABOUT DENDROCHRONOLOGY IN EPISODE 247 OF THE IN DEFENSE OF PLANTS PODCAST

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

Dung Seeds

Midgley, J., White, J., Johnson, S. et al. Faecal mimicry by seeds ensures dispersal by dung beetles. Nature Plants 1, 15141 (2015). https://doi.org/10.1038/nplants.2015.141

Photo by Nicola van Berkel (Nicky vB)

There are a lot of interesting seed dispersal mechanisms out there. It makes sense too because effective seed dispersal is one of the most important factors in a plant's life cycle. It is no wonder then that plants have evolved myriad ways to achieve this. Everything from wind to birds to mammals and even ants have been recruited for this task. Now, thanks to a group of researchers in South Africa, we can add dung beetles to this list.

That's right, dung beetles. These little insects are famous the world over for their dung rolling lifestyle. These industrious beetles are quite numerous and play an important role in the decomposition of feces on the landscape. Without them, the world would be a gross place. They don't do this for us, of course. Instead, dung beetles both consume the dung and lay their eggs on the balls. They are often seen rolling these balls across the landscape until they find the perfect spot to bury it where other dung-feeding animals won't find it. It is this habit that a plant known scientifically as Ceratocaryum argenteum has honed in on.

The seeds of this grass relative are hard and pungent. Researchers questioned why the plant would produce such smelly seeds. After all, the scent would hypothetically make it easier for seed predators to find them. However, the typical seed predators of this region such as birds and rodents show no real interest in them. What's more, when offered seeds directly, rodents only ate seeds in which the tough, smelly coat had been removed. Using cameras, the researchers studied the behavior of these animals time and time again. It was only after viewing hours of video that they made their discovery.

Although they weren't big enough to trip the cameras themselves, incidental footage caught dung beetles checking out the seeds and rolling them away. As it turns out, the scent and appearance (which closely mimics that of antelope dung) tricks the dung beetles into thinking they found the perfect meal. As such, the dung beetles do exactly what the plant needs - they bury the seeds. This is a dead end for the dung beetle. Only after a seed has been buried do they realize that it is both inedible and an unsuitable nursery. Nonetheless, the drive for reproduction is so strong that the plant is able to successfully trick the dung beetles into dispersing their seeds.

Photo Credit: Nicky vB (bit.ly/1WVgs0G) and Nature Plants

Further Reading:
http://www.nature.com/articles/nplants2015141

The Accidental Grain - How Rye Evolved Its Way Into Our Diet

Photo by Lotte Grønkjær licensed under CC BY-NC-SA 2.0

Humans have been altering the genomes of plants for a very long time. Nowhere is this more apparent than in the crops we grow. These botanical mutants are pampered beasts compared to their wild congeners. It is easy to see why some traits have been selected over others, whether it be larger leaves or fruit to munch on, smaller seeds to keep them out of our way, or tough rinds to make shipping easier. However, not all of our crops have been consciously bred for our consumption. Just as many weed species are adapting to herbicides today, some species of plant were able to adapt to the more archaic methods of early farming, which allowed them to avoid the ever watchful eye of the farmer.

This concept is known as Vavilovian mimicry (sometimes referred to as crop mimicry) and it is named after the Soviet botanist and geneticist Nikolai Vavilov (who was later imprisoned and starved to death by Stalin because of his firm stance on basic genetic principles). The idea is rather simple. At its core it involves artificial selection, albeit unintentional. A wild plant species finds certain forms of agriculture appealing. It becomes an apparent weed and the farmer begins to deal with it. Perhaps this plant is a close relative and thus looks quite similar to the crop in question. As the farmer weeds out plants that look different from the crop, they may be unintentionally selecting for individual weeds that more closely resemble the crop species. Over enough seasons, only those weeds that look enough like the crop survive and reproduce, sometimes to the point in which the two are almost indistinguishable.

Rye is an interesting example of this idea. Wild rye (Secale montanum) was not intentionally grown for food. It was a weed in the fields of other crops like wheat and barley. Both wheat and barley are annual plants, producing their edible seeds at the end of their first growing season. Wild rye, however, is a perennial and does not produce seed until at least its second season. Therefore, most wild rye plants growing in wheat or barely fields are killed at the end of the season when the field gets tilled. However, there are some mutant rye plants that occasionally pop up and produce seeds in their first year.

It is believed that these mutant annual rye were harvested unintentionally and reseeded season after season. Over time, other traits likely developed to help push rye into the spotlight for these early farmers. Like many wild grasses, wild rye has weak spindles (the part that holds the seed to the plant). In the wild, this allows for efficient seed dispersal. On the farm, this is not a desirable trait as you end up quickly losing the seeds you want to harvest. Again, by accidentally selecting for mutants that also had thicker spindles and thus held on to their seeds, farmers were unintentionally domesticating rye to parallel other cereal crops. It is believed that oats (Avena sterilis) also originated in this manner.

Photo Credit: Lotte Grønkjær (http://bit.ly/1xMEfVw)

Further Reading: [1] [2]

Bark!

Photos by SNappa2006 (CC BY 2.0), nutmeg66 (CC BY-NC-ND 2.0), Eli Sagor (CC BY-NC 2.0), and Randy McRoberts (CC BY 2.0)

Say "tree bark" and everyone knows what you're talking about. We learn at an early age that bark is something trees have. But what is bark? What is its purpose and why are there so many different kinds? Indeed, there would seem to be as many different types of bark as there are trees. It can even be used as a diagnostic feature, allowing tree enthusiasts to tease apart what kind of tree they are looking at. Bark is not only fascinating, it serves a serious adaptive purpose as well. To begin to understand bark, we must first look at how it is formed.

To start out, bark isn't a very technical term. Bark isn't even a single type of tissue. Instead, bark encompasses several different kinds of tissues. If you remember back to Plant Growth 101, you may have heard the word "cambium" get thrown around. Cambium is a layer of actively dividing tissue sandwiched between the xylem and the phloem in the stems and roots of plants. As this layer grows and divides, the inside cells become the xylem whereas the outside cells become the phloem. 

Successive divisions produce what is known as secondary phloem. This is where the bark begins. On the outside of this secondary phloem are three rings of tissues collectively referred to as the "periderm." It is the periderm which is responsible for the distinctive bark patterns we see. As a layer of cells called the "cork cambium" divides, the outer layer becomes cork. These cells die as soon as they are fully developed. This layer is most obvious in smooth bark species such as beech. 

Similar to insect growth, however, the growth of the insides of a tree will eventually outpace the bark. When this happens, the periderm begins to split and cracks will begin to appear in the bark. This phenomenon is most readily visible in trees like red oaks. When this starts to happen, cells within the secondary phloem begin to divide. This forms a new periderm underneath the old one. The cumulative result of this results in alternating layers of old periderm tissue referred to as "rhytidome." 

This gives trees like black cherry their scaly appearance or, if the rhytidome consists of tight layers, the characteristic ridges of white ash and white oak. Essentially, the distribution and growth pattern of the periderm gives the tree its bark characteristics. But why do trees do this? Why is bark there in the first place?

The dominant role of bark is protection. Without it, vital vascular tissues risk being damaged and the tree would rapidly loose water. It also protects the tree from pests and pathogens. The cell walls of cork contain high amounts of suberin, a waxy substance that protects against desiccation, insect attack, as well as fungal and bacterial infection. Thick bark can also insulate trees from fire. 

Countless aspects of the environment have influenced the evolution of tree bark. In some species such as aspen or sycamore, the trunk and stems function as additional photosynthetic organs. In these species, cork layers are thin and often flaky. Shedding these thin layers of bark ensures that buildup of mosses, lichens, and other epiphytes doesn't interfere with photosynthesis. The white substance on paper birch bark not only inhibits fungal growth, it also helps prevent desiccation while at the same time making it distasteful for browsing insects and mammals alike.

When you consider all the different roles that bark can play, it is no wonder then that there are so many different kinds. This is only the tip of the ice berg. Entire scientific careers have been devoted to understanding this group of tissues. For now, winter is an excellent time to start noticing bark. Take some time and get to know the trees around you for their bark rather than their leaves.

Photo Credits: Eli Sagor (bit.ly/1OTnA8H), Randy McRoberts (bit.ly/1PgzH35), Lotus Johnson (bit.ly/1JyVt1E), SNappa2006 (bit.ly/1TkjHil), and nutmeg66 (bit.ly/1QwyZQ8)

Further Reading:
http://www.botgard.ucla.edu/

html/botanytextbooks/generalbotany

/barkfeatures/typesofbark.html

http://dendro.cnre.vt.edu/forestbiolog

y/cambium2_no_scene_1.swf

http://life9e.sinauer.com/life9e/pages

/34/342001.html

http://www.botgard.ucla.edu/html/bo

tanytextbooks/generalbotany/barkfe

atures/