The Giant Genomes of Geophytes

Canopy plant (Paris japonica) Photo by Radek Szuban licensed under CC BY-NC 2.0

A geophyte is any plant with a short, seasonal lifestyle and some form of underground storage organ ( bulb, tuber, thick rhizome, etc.). Plants hailing from a variety of families fall into this category. However, they share more than just a similar life history. A disproportionate amount of geophytic plants also possess massive genomes. 

As we have discussed in previous posts, life isn't easy for geophytes. Cold temperatures, a short growing season, and plenty of hungry herbivores represent countless hurdles that must be overcome. That is why many geophytes opt for rapid growth as soon as conditions are right. However, they don't do this via rapid cell division. 

Dutchman's breeches (Dicentra cucullaria) emerging with preformed buds.

Instead, geophytes spend the "dormant" months pre-growing all of their organs. What's more, the cells that make up their leaves and flowers are generally much larger than cells found in non-geophytes. This is where that large genome comes into plant. If they had to wait until the first few weeks of spring to start their development, a large genome would only get in the way. Their dormant season growth means that these plants don't have to worry about streamlining the process of cellular division. They can take their time. 

As such, an accumulation of genetic material isn't detrimental. Instead, it may actually be quite beneficial for geophytes. Associated with large genomes are things like larger stomata, which helps these plants better regulate their water needs. The large genomes may very well be the reason that many geophytic plants are so good at taking advantage of such ephemeral growing conditions. 

When the right conditions present themselves, geophytes don't waste time. Pre-formed organs like leaves and flowers simply have to fill with water instead of having to wait for tissues to divide and differentiate. Water is plentiful during the spring so geophytes can rely on turgor pressure within their large cells for stability rather than investing in thick cell walls. That is why so many spring blooming plants feel so fleshy to the touch. 

Taken together, we can see how large genomes and a unique growth strategy have allowed these plants to exploit seasonally available habitats. It is worth noting, however, that this is far from the complete picture. With such a wide variety of plant species adopting a geophytic lifestyle, we still have a lot to learn about the secret lives of these plants.

Photo Credits: [1] [2]

Further Reading: [1]

The Hunt

This week we are going on the hunt for a small member of the carrot family known as the harbinger of spring (Erigenia bulbosa). Along the way we meet a handful of interesting plant species. Will we find our quarry? Watch and find out...

Producer, Writer, Creator, Host:
Matt Candeias (www.indefenseofplants.com)

Producer, Editor, Camera:
Grant Czadzeck (www.grantczadzeck.com)

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Early Spring Botanizing

SURPRISE!

Many have commented that a video component was lacking from the hiking podcasts. I have teamed up with filmmaker/producer Grant Czadzeck (www.grantczadzeck.com) to bring you a visual botanizing experience. I'm not sure how regular this will become but let us know what you think. In the mean time, please enjoy this early spring hike in central Illinois.

Spring Surprise on the Tallgrass Prairie

I have no frame of reference for spring on the tallgrass prairie. Everything is new to me. It is amazing to see what starts to come up before all of the grasses wake up and make things a lot harder to find. Diminutive herbs take advantage of sunlight while they can. What I also like is how well certain species stand out against a backdrop of last year's dry stems. This is how I was able to find wild hyacinth (Camassia scilloides). 

The first time I laid eyes on this species, I was actually looking for birds. The spot I was in is known for harboring pheasants. I could hear the males calling but I was having a hard time locating these colorful birds. As I scanned the prairie for shots of color, something else caught my eye. From where I was standing, it looked like a green stick covered in foam. I couldn't quite make out enough detail. I knew it had to be a plant but the search imagine simply wasn't there. I had to investigate. 

Gingerly I tip toed out into the grasses trying to avoid stepping on emerging vegetation. Luckily some deer had already beat a path pretty close to where this mystery plant was growing. When I was only a few yards away I quickly realized what I was seeing. It was a small patch of wild hyacinth. From a distance it was hard to resolve the outline of the tightly packed flowers. From up close, however, it is one of the most stunning spring displays I have ever seen. 

They were covered in ants. As it turns out, these flowers produce copious amounts of nectar. Whereas ants offer nothing in the way of pollination, myriad other insects like flies, bees, butterflies, and wasps visit these blooms in search of a sweet, energy-rich meal. This plant seems to have no trouble getting pollinated. This is a spring species, emerging from an underground bulb not unlike the hyacinths you buy at nurseries. It has slender, grass-like foliage that isn't always apparent mixed in with all of the other vegetation. 

I was a little surprised that such an obvious plant could exist unharmed so near a deer path until I did some research. Like many of its relatives, wild hyacinth is quite toxic to mammals. As such, the deer were smart to pass it up. After years of seeing nothing but its introduced Asian relatives, I was quite happy to be meeting an eastern species native to North America. 

Further Reading:

http://bit.ly/1NBPF9z

Dwarf Larkspur

There are certain genera that I almost always encounter in a garden setting. These are usually gaudy cultivars from other continents. This is especially true for Delphiniums. Since I moved back east, the only Delphiniums I see are garden varieties. All of that changed when I moved to Illinois. During one of my first day hikes in the Midwest, I had the pleasure of meeting a Delphinium I had never met before. What's more, I managed to stumble upon a patch of forest that boasted a rather large population. The species in question is the dwarf larkspur (Delphinium tricorne) and it is a plant worth knowing. 

Dwarf larkspur is native to a good chunk of the eastern United States, only absent from the northeastern and southeastern portions. It is a spring bloomer, flowering for about three weeks in late spring. The inflorescence this plant produces is stunning to say the least. If you're lucky enough to find yourself surrounded by these plants like I was, its as if the entire forest floor is awash in a sea of deep purple. 

The flowers can only be pollinated by queen bumblebees and hummingbirds. Whereas other insects will visit the flowers, the morphology is such that they are not effective pollinators. By the beginning of summer, the plants will have produced their seeds. At this time, however, the embryo within is not yet mature. It will not mature until the coming fall. Dwarf larkspur embryos do not begin to grow until temperatures have dropped to around 5 °C (41 °F). Then and only then will the seeds be ready to germinate, all in time for the arrival of spring. 

Like nearly all members of the buttercup family, the dwarf larkspur produces toxic alkaloids. Because of this, few herbivores will chance a nibble. Unfortunately for Delphiniums across North America, this fact has earned them a rather negative reputation among livestock owners. Nonetheless, these plants are wonderful and important ecological components wherever they are native. What's more, dwarf larkspur is growing in popularity among native gardeners looking to add some color to shaded portions of their landscape. 

Further Reading: [1] [2]

Meeting Blue-Eyed Mary

For some plant species, pictures will never do them justice. I realized this when I first laid eyes on a colony of blue-eyed Mary (Collinsia verna). I was smitten. These lovely little plants lined the trail of a floodplain forest here in central Illinois. It was the blue labellum that first caught my eye. After years of reading about and seeing pictures of these plants, meeting them in person was a real treat. 

C. verna is winter annual meaning its seeds germinate in the fall. The seedlings lie dormant under the leaf litter until spring warms enough for them to start growing. Growth is rapid. It doesn't take long for them to unfurl their first flowers. And wow, what flowers they have! 

The bicolored blooms are a real show stopper. The lower lip contrasts starkly with the white top. It's about as close to true blue as a flower can get. Not only are they beautiful, the flowers are marvels of evolution, exquisitely primed for pollination by large, spring-hardy insects. When something the size of a bumble bee lands on the flower, the lower lip parts down the middle, thrusting the reproductive bits up against the abdomen. This plant doesn't take any chances. 

Being an annual, C. verna can only persist via its seed bank. Populations can be eruptive, often appearing in mass after a disturbance clears the forest of competition. Most populations exist from year to year as much smaller patches that slowly build the seed bank in preparation for more favorable conditions in the future. Because of its annual life cycle, C. verna can be rather sensitive to habitat destruction. 

Seeing this plant with my own eyes far exceeded my expectations. It was one of those moments that I couldn't peel myself away from. I love spring ephemerals and this species has skyrocketed to the top of my list. Its beauty is made all the more wonderful by its ephemeral nature. Enjoy them while they last as it may be some time before you see them again. 

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

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]
 

Mayapple

All across eastern North America, one of my all time favorite wildflowers is coming into bloom. Looking like some sort of strange, tropical umbrella, mayapple (Podophyllum peltatum) is more easily recognizable by its overall appearance than its flowers. However, bend down and take a look under any plant with two leaves and you will be rewarded by one heck of a bloom. 

At home in the family Berberidaceae, the genus Podophyllum is predominantly Asian. Mayapple is the only species within this genus found anywhere else in the world. Mayapples exhibit two forms of reproduction, rhizomatous and sexual. When you see a great big stand of mayapple in the forest, there is a good chance they are all genetically identical. The rhizomes spread out underground, throwing up new plants as they go. This method of asexual reproduction has interesting implications for how this plant reproduces sexually. 

Mayapples will not self-pollinate. They need to cross with a genetically different individual for proper seed set. This can be troublesome in that mayapple flowers do not produce nectar and bees quickly become savvy to this and are less likely to visit multiple different patches of flowering mayapples consecutively. This is where neighboring flowers come into play. Research has shown that mayapples patches growing near flowering plants that do offer rewards to pollinators are significantly more likely to be pollinated themselves. Apparently bees aren’t as dissuaded by mayapples ruse when there are plenty of other meals to be had.

For mayapples, flowering brings with it an additional set of challenges. It takes a lot of energy to produce flowers, fruits, and seeds. Research has also demonstrated that flowering and fruit production in mayapples significantly decreases the chances of flowering in the future and significantly increases the likelihood of the plants demise. Still, enough plants survive long enough to flower multiple times throughout their life. 

Photo by Nicholas A. Tonelli licensed under CC BY 2.0

Mayapples, as the common name suggests, produce rather large fruit that turns a bright yellow when ripe. This is the only time in which consuming a piece of mayapple is safe as this species is highly toxic. This does not seem to deter other animals though. In my experience, fruits are short lived on the plant, quickly being gobbled up by raccoons and the like. The most interesting aspect of mayapple ecology to me is that, in at least part of its range, mayapple relies on box turtles as their main seed dispersers. Box turtles relish the fruit and seeds passing through the gut of the turtle are much more likely to germinate. All in all this is a familiar friend that never disappoints. If you are lucky enough to live where mayapples are native, get outside and experience a mayapple bloom for yourself. You will be very glad that you did!

Photo Credits: [2] [3]

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

Trillium

Trillium. The very name is synonymous with spring wherever they grow. Even the non-botanically minded amongst us could probably pick one out of a lineup. This wonderful genus holds such a special place in my heart and I anxiously await their return every year. The journey from seed to flowering plant is an arduous one for a trillium and some may take for granted just how much time has elapsed from the moment the first root pushed through the seed coat to the glorious flowers we admire each spring. The story of a Trillium, like any other plant, starts with a seed.

As with many other spring ephemerals, Trilliums belong to that group of plants that utilize ants as seed dispersers. Once underground in an ant midden, a Trillium seed plays the waiting game. Known as double dormancy, their seeds germinate in two phases. After a year underground, a root will appear followed by an immature rhizome and cotyledon. Here the plant remains, living off of the massive store of sunlight saved up in the endosperm for yet another year. Following this second year underground, the plant will throw up its first leaf.

In its fourth year of growth, the Trillium seedling will finally produce the characteristic whorl of 3 leaves we are familiar with. Now the real waiting game begins. Growing for such a short period of time each year and often in shady conditions, Trilliums must bide their time before enough energy is saved up to produce a flower. In an optimal setting, it can take a single Trillium 7 to 8 years to produce a flower. If conditions aren't the best, then it may take upwards of 10 years! Slow and steady wins the race in the genus Trillium. A large population of flowering Trillium could easily be 40 or 50 years old!

Sadly, when you couple this slow lifestyle with their undeniable beauty, you begin to spell disaster for wild trillium populations. A plant that takes that long to germinate and flower isn't the most marketable species for most nurseries and, as a result, Trillium are some of the most frequently poached plants in the wild. Because of their slow growth rate, poached populations rarely recover and small plots of land can quickly be cleared of Trilliums by a few greedy people. Leave wild Trilliums in the wild! 

Further Reading:

http://www.trilliumsunlimited.com/resources/3-1NPJ18-20.pdf

http://www.trilliumresearch.org/

Echoes of a Glacial Past

Climate change is often talked about in the context of direct effects on species. However, as John Muir so eloquently put it, "When we try to pick out anything by itself, we find it hitched to everything else in the Universe." In essence, nothing is ever black and white and the research I am writing about today illustrates this fact quite well.

Ants and plants have some very intricate interactions. A multitude of plant species rely on ants as their seed dispersers. Many of these plant species are spring ephemerals that take advantage of the fact that there is little else for ants to eat in the early spring by attaching fatty capsules to their seeds that are very attractive to foraging ant species. We refer to seed dispersal by ants as “myrmecochory.”

There are two big players in the foraging ant communities of eastern North America, the warm adapted Aphaenogaster rudis and the cold adapted Aphaenogaster picea. The cold adapted A. picea emerges from winter dormancy early in the spring while the warm adapted species emerges from dormancy much later in the spring. In the southern portions of their range, A. rudis outcompetes A. picea.

What is the big deal? Well, the researchers looked at two plant species that rely on these ants for seed dispersal, Hepatica nobilis and Hexastylis arifolia. Hepatica nobilis sets seed early in the spring, relying on ant species like A. picea to disperse its seed whereas Hexastylis arifolia sets seed late in spring, which is prime time for A. rudis. Researchers noticed that, in the southern portions of their range where A. picea had been displaced, Hepatica has a very clumped and patchy growth habit where farther north it did not. Hexastylis on the other hand seemed to have a more normal growth pattern in the south.

By performing some transplanting experiments and examining foraging and seed dispersal, they found that the absence of A. picea in the south spelled ecological disaster for Hepatica. It continues to set seed but because A. rudis emerges long after seed set, it is not filling the gap left by the missing A. picea. Hexastylis, which only grows in the south and sets seed much later, does just fine with the warm adapted A. rudis. Farther north where A. picea still rules, Hepatica has no trouble with seed dispersal but Hexastylis drops out of the ecosystem entirely. In essence, because of warming climate trends since the end of the Pleistocene, Hepatica is falling out of sync with its mutualistic ant partner in the southern portions of its range and, in time, may become extirpated.

Further Reading: [1]

When One Becomes Two

One of the most stunning spring flowering plants in the eastern forests has to be blue cohosh (Caulophyllum spp.). Around this time of year they begin poking up through the leaf litter, their deep purple stems gradually giving way to shades of blue and green as the leaves and flowers expand into the springtime sun. They seem almost otherworldly and finding them among the speckled leaves of trout lily is a sight I will never tire of.

For as long as it has been known, North America's Caulophyllum has been considered a single species, Caulophyllum thalictroides. The specific epithet hints at how similar this species can look to the meadow rues (Thalictrum spp.). However, a keen observer could tell you that there are apparent differences between some blue cohosh populations, especially in the northeast. Some cohosh flower much earlier than others. Also, there are differences in flower color as well. Some plants sport flowers decked in deep maroon whereas others are pale green. These differences have led some authors to list the purple flowering variety as a subspecies, Caulophyllum thalictroides giganteum.

Caulophyllum thalictroides

Photo by Tom Potterfield licensed under CC BY-NC-SA 2.0

More recently, however, it has become apparent that these two varieties may actually be separate species. Though their ranges overlap, what is now being called Caulophyllum giganteum is distributed much farther north than C. thalictroides. The key differences between these two has to do with flowering time. If these two species become reproductively active at different times, then they are in fact reproductively isolated from one another. Though they can hybridize, the resulting seeds experience reduced viability and do not perform as well as either parent.

Photo Credit: Tom Potterfield (http://bit.ly/1E0JcQ5)

Further Reading: [1] [2]