The Shrubs of Iridaceae

Did you know there are shrubs in the iris family? I didn't either until quite recently. I had the distinct honor of getting to tour the collections of Martin Grantham, a resident of the Bay Area and quite possibly the most talented horticulturist I have ever met. Martin has had quite a bit of luck with these plants and because of this, I was able to meet a handful of them growing quite happily in large containers. There are some things in life that your brain just simply isn't prepared to take in. The shrubby iriads are one of them.

The true shrubby species all hail from a subfamily of Iridaceae coined Nivenioideae. This is not a single grouping of all shrubby genera. It contains other genera that look a lot more like what we would consider an iris. Nivenioideae as a whole is considered to be pretty derived for the iris family, with the shrubby species serving as an excellent example of how bizarrely unique the subfamily really is. In total, there are three genera of shrubby iriads - Klattia, Nivenia, and Witsenia, all of which are native to South Africa. The former contain a small handful of species whereas the latter has only a single representative.

Once you get past the initial shock and awe of what you have just laid eyes on, their membership in the iris family becomes a bit more apparent. Though there is great variation in size, the species I encountered all looked roughly like long, slender sticks with multiple iris-like fans of leaves jutting out. Like most members of the family, the flowers of this group are spectacular. In the wild they are visited by long tongue bees and flies.

Overall this group is poorly understood. Some molecular phylogenetic work has been performed but it is by no means concrete. More attention may result in either the addition or subtraction of species. The most thorough treatment on the shrubby iriads comes from a monograph written by Dr. Peter Goldblatt as well as a handful of horticultural articles written by those lucky enough to have had some success in growing these plants (see Martin's essay on his experiences - http://bit.ly/2pStMZ4). Like most of South Africa's unique flora, these plants are at threatened by habitat destruction, invasive species, and climate change. Luckily many of these species have caught the attention of folks like Martin who have put in the time and dedication into understanding their germination and growth requirements.
 

Seeing these plants in person was breathtaking. Not only was I completely flabbergasted at their appearance, the fact that plants like this exist is a testament to the wild diversity of life this planet supports. I never tire of meeting new plant species and this is one encounter I won't soon forget. Just when you think you are starting to understand plant diversity, plants like these show up to remind you that you have just barely scratched the surface.

Photo Credit: [1]


Further Reading: [1] [2]

The Power of Leaves

When we think of the dominance of flowering plants on the landscape, we usually invoke the evolution of flowers and seed characteristics like endosperm and fruit. However, evolutionary adaptations in the structure of the angiosperm leaf may have been one of the most critical factors in the massive diversification that elevated them to their dominant position on the landscape today. 

Leaves are the primary organs used in water and gas exchange. They are the centers of photosynthesis, allowing plants to take energy from our closest star and turn it into food. To optimize this system, plants must balance water loss with transpiration in order to maximize their energy gain. This requires a complex plumbing system that can deliver water where it needs to be. It makes sense that plant physiology should maximize vein production, however, there are tradeoffs in doing so. Veins are not only costly to construct, they also displace valuable photosynthetic machinery. 

It appears that this is something that flowering plants do quite well. Because leaves fossilize with magnificent detail, researchers are able to look back in time through 400 million years of leaf evolution. What they found is quite incredible. There appears to be a consistent pattern in the vein densities between flowering and non-flowering plants. The densities found in angiosperm leaves both past and present are orders of magnitude higher than all non-flowering plants. These high densities are unique to flowering plants alone. 

This innovation in leaf physiology allowed flowering plants to maintain transpiration and carbon assimilation rates that are three and four times higher than those of non-flowering plants. This gives them a competitive edge across a multitude of different environments. The evolution of such dense vein structure also had major ramifications on the environment. 

The massive change in transpiration rates among the angiosperm lineage is likely to have completely changed the way water moved through the environment. These effects would be most extreme in tropical regions. Today, transpiration from tropical forests account for 30-50% of precipitation. A lot of this has to do with patterns in the intertropical convergence zone, which ensures that such humid conditions can be maintained. However, in areas outside of this zone such as in the Amazon, a high abundance of flowering plants with their increased rates of transpiration enhances the amount of rainfall and thus forms a sort of positive feedback.

Because precipitation is the single greatest factor in maintaining plant diversity in these regions, increases in rainfall due to angiosperm transpiration effectively helps to maintain such diversity. As angiosperms rose to dominance, this effect would have propagated throughout the ecosystems of the world. Plants really are the ultimate ecosystem engineers. 

Photo Credit: Bourassamr (Wikimedia Commons)

Further Reading: [1]

Purple Mouse Ears

Mimulus douglasii

The success of some plant species comes from the simple fact that they can grow where other plants can't. Such is the case for the purple mouse ear (Mimulus/Diplacus douglasii). Native to northern California and Oregon, this tiny plant can most often be found growing in serpentine soils. Finding it can get tricky as it is quite diminutive in size and doesn't always produce its outlandishly showy flowers. 

Mature plants stand roughly 4 cm in height. When produced, the flowers are rather large and showy, often much larger than the rest of the plant. Unlike other members of the genus, the bottom lip of the tubular flowers has been reduced so much that it might as well not exist. Instead, the two top petals dominate the display, giving this plant a cartoonish outline of a mouse. As you can see, they are incredibly showy. 

This plant has to do what it can to ensure that it sets seed in any given growing season. Purple mouse ears are annual plants, so they only get one shot at reproduction. To make matters more difficult, they frequently grow in serpentine soils, which are low in essential nutrients and high in toxic metals like nickel, cobalt, and chromium. Despite these difficult conditions, purple mouse ears seem to benefit from the lack of competition on these traditionally toxic substrates. 

Cleistogamous flowers

Cleistogamous flowers

Plants don't always produce their showy floral displays. When times are tough, they opt for asexual reproduction. Instead of the big, showy flowers, plants will produce tiny flower buds that never open. These are called cleistogamous flowers. Instead, they simply self-pollinate, which ensures that the genes that allowed the parent to survive environmental hardships are guaranteed to make it into the next generation. For annuals whose entire life is wrapped up in a single season, sometimes its not worth taking any chances. 

Photo Credit: [1] 

Further Reading: [1] [2] 

Meet the Redbuds

Redbud (Cercis canadensis)

I look forward to the blooming of the redbuds (Cercis spp.) every spring. They can turn entire swaths of forest and roadside into a gentle pink haze. It's this beauty that has led to their popularity as an ornamental tree in many temperate landscapes. Aside from their appeal as a specimen tree, their evolutionary history and ecology is quite fascinating. What follows is a brief introduction to this wonderful genus.

Redbud (Cercis canadensis)

The redbuds belong to the genus Cercis, which resides in the legume family. In total, there are about 10 species disjunctly distributed between eastern and western North America, southern Europe, and eastern Asia. All of them are relatively small trees with beautiful pink flowers. Interestingly enough, unlike the vast majority of leguminous species, redbuds are not known to form root nodules and therefore do not form symbiotic relationships with nitrogen-fixing bacteria called rhizobia. This might have something to do with their preference for rich, forest soils. Until more work is done on the subject, its hard to say for sure.

One of the most interesting aspects of the redbuds are their flowers. We have already established that they are quite beautiful but their development makes them even more interesting. You have probably noticed that they are not borne on the tips of branches as is the case in many flowering tree species. Instead, they arise directly from the trunks and branches. This is called "cauliflory," which literally translates to "stem-flower." In older specimens, the trunks and branches become riddles with bumps from years of flower and seed production.

Redbud (Cercis canadensis)

It's difficult to make generalizations about this flowering strategy. What we do know is that it is most common in dense tropical forests. Some have suggests that producing flowers on trunks and stems makes them more available to small insects or other pollinators that are more common in forest understories. Others have suggested that it may have more to do with seed dispersal than pollination. Regardless of any potential fitness advantages cauliflory may incur, the appearance of a redbud covered in clusters of bright pink flowers is truly a sight to behold.

Further Reading: [1] [2] [3] [4] [5] [6]

Mighty Magnolias

Magnolias are one of those trees that even the non-botanically minded among us will easily recognize. They are one of the more popular plant groups grown as ornamentals and their symbolism throughout human history is quite interesting. But, for all this attention, few may realize how special magnolias really are. Did you know they they are one of the most ancient flowering plant lineages in existence?

Magnolias first came on to the scene somewhere around 95 million years ago. Although they are not representative of what the earliest flowering plants may have looked like, they do offer us some interesting insights into the evolution of flowers. To start with, the flower bud is enclosed in bracts (modified leaves) instead of more differentiated sepals. The "petals" themselves are not actually petals but tepals, which are also undifferentiated. The most striking aspect of magnolia flower morphology is in the actual reproductive structures themselves.

Magnolias evolved before there were bees. Because of this, the basic structure that makes them unique was in place long before bees could work as a selective pressure in pollination. Beetles are the real pollinators of magnolia flowers. The flowers have a hardened carpel to avoid damage by their gnawing mandibles as the feed. The beetles are after the protein-rich pollen. Because the beetles are interesting in pollen and pollen alone, the flowers mature in a way that ensures cross pollination. The male parts mature first and offer said pollen. The female parts of the flower are second to mature. They produce no reward for the beetles but are instead believed to mimic the male parts, ensuring that the beetles will spend some time exploring and thus effectively pollinating the flowers.

It is pretty neat to think that you don't necessarily have to track down a dawn redwood or a gingko to see a plant that has survived major extinction events. You can find magnolias very close to home with a keen eye. Looking at one, knowing that this is a piece of biology that has worked for millennia, is quite astounding in my opinion.

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

Meet Snorkelwort

If vernal pools are considered ephemeral then granite pools are downright fleeting. Any organism that specializes in such a habitat must be ready to deal with extremes. That is what makes a little plant known scientifically as Gratiola amphiantha so darn cool. It's what also makes it so darn threatened. 

This tiny member of the Plantaginaceae family is native to the Piedmont province of southeastern North America. It lives out its entire life in shallow pools that form in weathered granitic outcrops. One must really think about the specificity of this sort of habitat to truly appreciate what this little aquatic herb is up against. Pools must be deep enough to hold water just long enough but not too deep to allow normal plant succession. They must have just enough soil to allow these plants to take root but the soil must be thin enough to prevent other vegetation from taking over. They must also be low in nutrients to limit the growth of algae that would otherwise cloud the water. Needless to say, this makes suitable habitat for snorkelwort hard to come by. 

When such conditions are met, however, snorkelwort can be quite prolific. Seeds of this species germinate in late fall and early winter when only a thing veneer of water covers the equally thin soils. Individual plants form a small rosette that sits in wait until rains fill the tiny pools. Once submerged, the rosettes send up thin stem-like structures called scapes. These scapes terminate in two tiny bracts that float at the waters surface. Between the two bracts emerges tiny, white, five petaled flowers. Submerged flowers are also produced but these are cleistogamous flowers that never open and only self-pollinate. This ensures that at least some seeds are produced every growing season. 

When you consider all aspects of its ecology, it is no wonder that snorkelwort is teetering on the edge of extinction. The granitic pools in which it lives are very sensitive to change. It doesn't take much to make them totally unsuitable places to live. Protecting them alone is hard enough. Mining, pollution, littering, and even casual hikers can wipe out entire populations in an instant. Even populations living within the boarders of protected parks have been extirpated by hiking and littering. When you live on the edge, it doesn't take much to fall off. In total, only about 31 populations scattered through Alabama, Georgia, and South Carolina are all that remains of this overlooked little plant. 

The upside to all of this is that numerous stake holders, both public and private, are invested in the ongoing success of this species. Private land owners whose land supports snorkelwort populations are cooperating with botanists to ensure that this species continues to find what it needs to survive. Luckily a sizable chunk of the remaining populations are large enough to support ample genetic diversity and, at this point in time, don't seem to be at any risk of destruction. For a little plant like snorkelwort, a little attention can go a long way. If you know a spot where this interesting little plant grows, tread lightly and appreciate it from a safe distance. 

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

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

 

The World's Only (Known) Photosynthetic Vertebrate

You may be asking yourself right now why I have posted a picture of a salamander this morning. This is a plant blog after all! Well, what I am about to tell you may seem a bit crazy, but I assure you this discovery has opened up some doors that science never really considered a possibility before. The yellow spotted salamander (Ambystoma maculatum) is the first and only (known) photosynthetic vertebrate ever discovered!

That's right. You heard me. A photosynthetic animal. More accurately speaking, it is the embryos of this species that undergo photosynthesis. To understand why this happens we must back up a little bit. Yellow spotted salamanders are a species of mole salamander that can be found in wet areas of eastern North America. They spend most of their adult lives underground, hiding beneath logs and rocks in the forest, feeding on any manner of invertebrates. Once a year (around this time) adult yellow spotted salamanders undertake a massive migration down to the pools where they mate. On the first few warm, rainy nights, thousands of salamanders can be seen trucking their way to vernal pools and ponds to breed. It is an amazing sight to behold.

The thing about yellow spotted salamanders is they will only breed in fishless ponds. Their larvae would be an easy meal for many predatory fish species. The problem that arises out of this breeding strategy is that fishless ponds tend to be very low in oxygen. It has long been known that the eggs of this species form a symbiotic relationship with an algae. The algae produce oxygen for the developing embryo and the embryo feeds the algae via its nitrogen rich waste and CO2. This relationship was always thought to be external, that is until Ryan Kerney of Dalhousie University in Halifax, Nova Scotia discovered that embryos of a certain age actually had algae living within their cells.

They algae don't seem to start off inside the cells though. This may be why this relationship wasn't discovered earlier. Roger Hangarter at Indiana University found that it isn't until parts of the salamander's nervous system begin to develop that the algae move into the embryo and set up shop. The algae then reside near the salamander's mitochondria, which are the powerhouses of the cell. So where are the algae coming from? While more research needs to be done, Karney also discovered the presence of algae in the oviducts of adult female spotted salamanders. It is looking like mother salamanders are actually passing the algae on to their offspring. 

Though this is the first and only instance we know of this sort of photosynthetic relationship in vertebrate animals, this discovery has opened the door for exploring the possibility of other photosynthetic symbionts. It has also allowed scientists a different avenue to explore just how cells recognize and deal with foreign bodies. We live in such an amazing world!

Further Reading: [1] [2] [3]

 

The Fetid Adderstongue

"Fetid adderstongue" seems like a pretty ominous name for such a small and beautiful plant. Hailing from coastal North America, the genus Scoliopus is most at home in the deep shaded forests of California and Oregon. Spring is the best time to see these little lilies and once you know a little bit about their ecology, such encounters are made all the more interesting.

There are two species nestled within this genus - S. bigelovii and S. hallii. Both are similar in that they are plants of deep shaded environments, however, you are more likely to find S. hallii growing along the banks of wooded streams. As is typical of many members of the lily family, their flowers are quite beautiful in appearance. The trick is finding them. Though quite showy, they are rather small and their dark coloration causes them to blend in quite well in their shaded environments. That is all fine and dandy for a species that relies more on smell rather than looks to attract pollinators.

As the common name suggests, the flowers of the fetid adderstongues give off a bit of an odor. I have heard it best described as "musty." The flowers of these two species attract a lot of fungus gnats. Although these tiny little flies are generally viewed as sub par pollinators for most flowering plants, the fetid adderstongues seem to do quite well with them. What they lack in robust pollination behavior, they make up for in sheer numbers. There are a lot of fungus gnats hanging around wet, shaded forests.

The flowers themselves are borne on tall stalks. Though they look separate, they are actually an extension of a large, underground umbel. Once pollination has been achieved, the flower stalks begin to bend over putting the developing ovaries much closer to the ground. Each seed comes equip with a fleshy little attachment called an eliasome. These are essentially ant bait. Once mature, the seeds are released near the base of the parent. Hungry ants that are out foraging find the fleshy attachment much to their liking.

They bring the seeds back to the nest, remove the eliasomes, and discard the seed into a trash midden. Inside the ants nest, seeds are well protected, surrounded by nutrient-rich compost, and as some evidence is starting to suggest, guarded against damaging fungal invaders. In other words, the plants have tricked ants into planting their seeds for them. This is a very successful strategy that is adopted by many different plant species the world over.

Though small, the fetid adderstongues are two plants with a lot of character. They are definitely a species you want to keep an eye out for the next time you find yourself in the forests of western North America. If you do end up finding some, just take some time to think of all the interesting ecological interactions these small lilies maintain.

Photo Credits: [1] [2]

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

Cedar-Apple Rust

I have had my eye on these strange brown golf ball shaped growths growing on the twigs of a cedar in my neighborhood for about a year now. I first took notice of them late last spring. They looked pretty nasty but I knew they had to be something interesting. Indeed, interesting doesn't even come close to the reality. 

These odd little growths are actually a single stage in the complex life cycle of a group of fungi in the genus Gymnosporangium. Collectively they are referred to as cedar-apple galls. Its a group of fungi whose hosts include junipers and relatives of the apple. Wherever these two lineages coexist you are bound to find this fungus. 

Gymnosporangium have a rather interesting life cycle that includes multiple hosts. The golf ball shaped galls will appear on the twigs of a juniper nearly a year after being infected with spores. They grow in size until they reach a point in which they will barely fit in the palm of your hand. The gall itself is covered in a series of depressions, making it look quite out of place in a natural setting. After a year on the tree, the galls enter into their next stage of development. 

Usually triggered by the first warm rains of spring, strange gelatinous protrusions start to poke out of each depression on the gall's surface. These protrusions continue to swell until the entire gall is covered in bright orange finger-like masses. These are where the spores are produced. These spores, however, cannot infect another juniper. Instead, they need to land on the next host to complete their life cycle. 

If the spores land on a member of the family Rosaceae (though usually apples - genus Malus - are preferred), then the second stage of the life cycle begins. Spores can germinate on both the leaves and the fruit but instead of turning into a large brown gall, they take on a different appearance. This is what makes this fungus readily apparent as a type of rust. A patch of orange will begin to grow. Upon closer inspection one can see that the orange patch is actually a series of small cup-like structures full of spores. 

Come fall, the spores are ready to be dispersed by wind. With any luck, these spores will land back on a juniper tree and the cycle will start anew. Because of its propensity for apple crops, cedar-apple rust fungi are considered to be quite a pest. In a more natural setting, however, it is one of the most unique and interesting fungi you can find. It looks truly alien if you aren't already aware of its existence. 

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

Further Reading: [1] [2]

Seed Anchor

Epiphytic plants live out their entire lives on the trunks or branches of trees. Using their roots, they attach themselves tightly to the bark. Spend any amount of time in the tropics and it will become quite clear that such a lifestyle has been very successful for a plethora of different plant families. Still, living on a tree isn't easy. Epiphytic plants must overcome harsh conditions among or near the canopy.

One of the biggest challenges these plants face starts before they even germinate. This is especially true for orchids. Orchid seeds are more like spores than they are seeds. They are so small that thousands could fit inside of a thimble. Upon ripening, the dust-like seeds waft away on the slightest breeze. In order for epiphytic species to germinate and grow, their seeds must somehow anchor themselves in place on a trunk or branch. Inevitably most seeds are doomed to fail. They simply will not land in a suitable location. It stands to reason then that any adaptation that increases their chances of finding the right kind of habitat will be favored. That's where the strange coils on the tip of Chiloschista seeds, a genus of leafless orchids native to southeast Asia, New Guinea, and Australia, come in. For these orchids, this process is aided by some truly unique seed morphology.

Unlike most orchid seeds that are nothing more than a thin sheath surrounding a tiny embryo, the seeds of Chiloschista have additional parts. These "appendages," which are specialized seed coat cells, are tightly wound into coils. Upon contact with water, these coils shoot out like tiny grappling hooks that grab on to moss and bark alike. In doing so, they anchor the seed in place. By securing their hold on the trunk or branch of a tree, the seeds are much more likely to germinate and grow. This is one of the most extreme examples of seed specialization in the orchid family.

Photo Credit: [1] [2]

Further Reading: [1]

Meet Virginia Pennywort

Meet the pennywort gentian (Obolaria virginica). It is a plant of the southeast with its most northerly distribution being around Pennsylvania. I am a little obsessed with gentians so finding this plant is always a special treat. My first encounter left me a bit perplexed by its overall appearance, which is very compact. The leaves and flowers all seemed to be mashed together, competing for space. 

Its small stature and dark coloration cause it to blend in surprisingly well with the forest floor. You often don't see it until you are right on top of one. Something seems to be working well for the Virginia pennywort because once you find one, you usually find many more. Oddly enough, I most frequently see this species in its highest abundance on the side of well-trafficked trails. Add to that its highly reduced leaf area and you have a few traits that usually get me thinking about parasitic plants. Anecdotally speaking, I quite often find parasites near foot traffic. If I had to guess, I would say that it has something to do with root damage, however, I have no data to support such claims. That being said, the literature suggests I wasn't wrong in my suspicions.  

The roots of the Virginia pennywort are described as "coralloid", meaning they take on a structure reminiscent of some corals. This is usually a trait exhibited by species whose roots are closely associated with microbes such as cyanobacteria or certain fungi. Indeed, the roots of the Virginia pennywort are often infested with arbuscular mycorrhizae. Additionally, there is some molecular evidence to suggest that this species is at least partially mycoheterotrophic, meaning it gets some at least some of its nutrients parasitically from said mycorrhizal fungi. Isotope analysis demonstrated that the tissues of the Virginia pennywort were more enriched with isotopes of nitrogen than the surrounding vegetation.

It is a really neat plant to find. If you do, make sure to take some time with it and get down on its level for a closer look. You won't be disappointed!

Further Reading:
http://www.amjbot.org/content/97/8/1272.short

http://plants.usda.gov/java/profile?symbol=obvi

Red Nectar

No, your eyes are not playing tricks on you. This flower produces red nectar. Known scientifically as Nescodon mauritianus, this member of the bellflower family (Campanulaceae) grows only on the island of Mauritius. Although it is not alone in producing colored nectar (at least 60 other plant species do so as well) the striking contrast of the red nectar against the blue corolla had botanists wondering what exactly these plants are attracting.

Of course, the obvious answer were birds. It is no mystery that birds see in color much in the same way as us humans. However, multiple tests and observations demonstrated that birds were not the best pollinators for these flowers. In fact, the birds functioned mainly as thieves, stealing nectar without actually coming into contact with any of the necessary floral parts. The same thing happened to a Mauritian relative of the mallows named Trochetia blackburniana, which also produces colored nectar. 

To better understand the signalling mechanisms of these flowers, a team of researchers utilized a series of floral models. By filling the models with different colored nectar, they were able to better understand what they are attracting. As it turns out, the answer to this mystery are geckos. 

Phelsuma geckos visiting the flowers of Trochetia blackburniana (left) and flower models (right). Hansen et al. 2006

Phelsuma geckos visiting the flowers of Trochetia blackburniana (left) and flower models (right). Hansen et al. 2006

Living alongside these plants is a genus of day gecko called Phelsuma. They are endemic to Mauritius and can frequently be found visiting nectar-producing flowers in search of energy-rich nectar. By observing how the geckos responded to various color combinations, the team was able to discover that these geckos seem to prefer red and yellow nectar over clear. What's more, their feeding habits once inside the flower puts them in direct contact with the anthers and the stigma. Thus, the geckos function as the most effective pollinators for these plants. 

The team now feels that the colored nectar of these species serves as an honest reward for pollinating geckos. It is a stark indication that a reward is present. It is possible that because these geckos rely on brightly colored markings when interacting with each other, the selection for brightly colored floral signals has been favored in the evolution of these gecko pollinated plants. More work needs to be done to say for certain. What we do know for sure is that these day geckos are important pollinators in Mauritian ecosystems.

Photo Credits: [1] [2]

Further Reading: [1]

 

Begonia's Hawaiian Cousin

Begoniaceae is a strange family. It consists of two genera - Begonia, which is comprised of roughly 1,400 species, and Hillebrandia, which consists of a single species endemic to Hawai'i (Symbegonia has since been placed back into Begonia). Although I adore the entire family, its that single genus that is the focus of our attention today. Far from being a strange one-off, Hillebrandia has a fascinating evolutionary history.

The sole species, Hillebrandia sandwicensis, is the only member of the family native to Hawai'i. It differs from the genus Begonia in characters such as its petals, which are more numerous and more differentiated, its ovaries, which do not completely close, as well as various morphological characteristics of its fruit and pollen, which I won't go into here. It occurs naturally only on the islands of Kauai, Maui, and Molokai where it inhabits wet ravines in montane rainforest zones. Nowhere is this species considered abundant. 

Since its discovery in 1866, H. sandwicensis has been the object of much curiosity. Where did it originate? How old of a species is it? How did it get to Hawai'i? Thanks to some molecular work, a few of these questions are becoming a bit more clear. For starters, we can now confidently say that Hillebrandia is a sister lineage to all other Begonias. This in turn has provided a crucial step in our understanding of its biogeography.

Molecular dating techniques place the genus Hillebrandia at about 51–65 million years old, much older than any of the Hawaiian islands. As such, it is likely that this lineage is not the results of an adaptive radiation like we see in most of the archipelago's flora and fauna. Instead, it is now believed that H. sandwicensis is the only known relict species in Hawaiian flora. In other words, the ancestor of H. sandwicensis did not arrive at Hawai'i and then evolve into the species we know today. Instead, it is more likely that the lineage arose elsewhere and then, through a random long-distance seed dispersal event, made it to Hawai'i's oldest islands some 30 million years ago and has been island hopping to younger islands ever since. 

Although its recent history and geographic origins are still open to much speculation, the story of this unique genus has gotten a bit clearer. Its status as Hawai'i's only known relict plant species is quite exciting to say the least. What we can say for sure is that its history was likely full of serendipity that should be celebrated each time someone has an encounter with this lovely Hawaiian plant.

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.

Thanks, Ducks!

Recent research suggests that certain duck species are crucial for maintaining wetland plant diversity in highly fragmented landscapes. Functioning wetlands are becoming more and more isolated each year. As more land is gobbled up for farming and development, the ability for plants to get their seeds into new habitats is made even more difficult. Luckily, many plants utilize animals for this job. Seeds can become stuck in fur or feathers, and some can even pass through the gut unharmed. What's more, animals can move great distances in a short amount of time. For wetland plants, the daily movements of ducks seems to be paramount. 

By tracking the daily movements of mallards, a team of researchers from Utretch University were able to quantify how crucial these water fowl are for moving seeds around. What they found was quite remarkable. In autumn and winter, the diet of mallards switches over to seeds. Not all seeds that a mallard eats get digested. Many pass through the gut unharmed. Additionally, mallards are strong flyers. On any given day they can travel great distances in search of winter foraging grounds. In the evenings, they return to roosting sites with a high degree of fidelity. 

The research team was able to demonstrate that their movements cover even greater distances in highly fragmented landscapes. It's these daily migrations that are playing a major role in maintaining plant diversity between distant wetlands. This is especially important for wetlands that function as roost sites. Whereas mallards distribute around 7% of the surviving seeds they eat among foraging sites, that number jumps to 34% for surviving seeds at roost sites. Given the sheer number of mallards on the landscape, these estimates can really add up. 

It is likely that without mallards, North American wetlands would be much less diverse given their increasingly isolated nature. However, not all seeds are dispersed equally. Small seeds are far more likely to pass through the gut of a duck unharmed, meaning only a portion of the plant species that grow in these habitats are getting a helping hand (wing?). Still, the importance of these birds cannot be overlooked. The next time you see a mallard, thank it for maintaining wetland plant diversity. 

Photo Credits: [1] [2]

Further Reading: [1]

The Plant That Grows a Perch

For flowering plants, entering into an evolutionary relationship with birds as pollinators can be a costly endeavor. It can take a lot of energy to coax birds to their blossoms. On the whole, bird pollinated flowers are generally larger, sturdier, and produce more nectar. They tend to invest heavily in pigmentation. The plants themselves are often more robust as well. Unlike hummingbirds, which usually hover as they feed, other nectar-feeding birds require a perch. Often this is simply a stout branch or a stem, however, a plant endemic to South Africa takes bird perches to a whole new level - it grows one. 

Meet the rat's tail (Babiana ringens). Though not readily apparent, this bizarre looking plant is a member of the iris family. It is endemic to the Cape Province of South Africa where it can be found growing in sandy soils. It produces a fan of erect, grass-like leaves and, when conditions are right, a side branch full of red tubular flowers. This is when things get a bit strange. 

From that flowering stalk emerges a much longer stalk that is said to resemble the tail of a rat, earning this plant its common name. This stalk rises well above the rest of the flowers. If you look closely at the tip of this stalk you will quickly realize this is yet another flower stalk, though this one is sterile. Such a stalk may seem like a strange structure for this plant to produce until you consider its pollinators. 

The rat's tail has entered into an evolutionary relationship with a species of bird known as the malachite sunbird (Nectarina femosa). To access the nectar within, the malachite sunbird can't simply walk up to and shove its face down into the flowers. Instead, it must access them from above. To do so, it perches itself on the rigid sterile flower stalk. Once in position, the malachite sunbird can dip its long, down-curved beak directly into the flowers. This is exactly what the plant requires. In this perched position, pollen is brushed all over its chest. 

babssunny.jpg

Researchers wanted to know how obligate this relationship really was. By removing the perch on selected plants, they were able to demonstrate a reduction in pollination success . Specifically, male sunbirds were less likely to visit plants without the perch stalk. Although these plants are capable of self pollinating, like any sexually reproducing organism, outcrossing is the key to success. By offering the birds a sturdy perch allowing them exclusive access to their nectar, the plants guarantee sunbird fidelity.  

Photo Credits: [1] [2]

Further Reading: [1]

Spring Has Sprung Earlier

Phenology is defined as "the study of cyclic and seasonal natural phenomenon, especially in relation to climate, plant, and animal life." Whether its deciding when to plant certain crops or when to start taking your allergy medication, our lives are intricately tied to such cycles. The study of phenology has other applications as well. By and large, it is one of the best methods we have in understanding the effects of climate change on ecosystems around the globe. 

For plants, phenology can be applied to a variety of things. We use it every time we take note of the first signs of leaf out, the first flowers to open, or the emergence of insect herbivores.  In the temperate zones of the world, phenology plays a considerable role in helping us track the emergence of spring and the onset of fall. As we collect more and more data on how global climates are changing, phenology is confirming what many climate change models have predicted - spring is starting earlier and fall is lasting longer.

Researchers at the USA National Phenology Network have created a series of maps that illustrate the early onset of spring by using decades worth of data on leaf out. Leaf out is controlled by a variety of factors such as the length of chilling temperatures in winter, the rate of heat accumulation in the spring, and photoperiod. Still, for woody species, the timing of leaf out is strongly tied to changes in local climate. And, although it varies from year to year and from species to species, the overall trend has been one in which plants are emerging much earlier than they have in the past.

https://www.usanpn.org/data/spring

For the southern United States, the difference is quite startling. Spring leaf out is happening as much as 20 days earlier than it has in past decades. Stark differences between current and past leaf out dates are called "anomalies" and the 2017 anomaly in the southern United States is one of the most extreme on record.

How this is going to alter ecosystems is hard to predict. The extended growing seasons are likely to increase productivity for many plant species, however, this will also change competitive interactions among species in the long term. Early leaf out also comes with increased risk of frost damage. Cold snaps are still quite possible, especially in February and March, and these can cause serious damage to leaves and branches. Such damage can result in a reduction of productivity for these species.

Changes in leaf out dates are not only going to affect individual species or even just the plants themselves. Changes in natural cycles such as leaf out and flowering can have ramifications across entire landscapes. Mismatches in leaf emergence and insect herbivores, or flowers and pollinators have the potential to alter entire food webs. It is hard to make predictions on exactly how ecosystems are going to respond but what we can say is that things are already changing and they are doing so more rapidly than they have in a very long time. 

For these reasons and so many more, the study of phenology in natural systems is crucial for understanding how the natural world is changing. Although we have impressive amounts of data to draw from, we still have a lot to learn. The great news is that anyone can partake in phenological data collection. Phenology offers many great citizen science opportunities. Anyone and everyone can get involved. You can join the National Phenology Network in their effort to track phenological changes in your neighborhood. Check out this link to learn more: USA National Phenology Network

Further Reading: [1] [2]