The Lowly Lawn Orchid

A new year and a new orchid. It didn't take long for me to spot this little plant poking up between the succulent leaves of a potted aloe. My elation was short lived though. Alas, the sun was setting and I didn't have a flashlight or my camera. I was much luckier the next day. Actually, I shouldn't say lucky. This orchid isn't uncommon.

Meet the lawn orchid (Zeuxine strateumatica). Originally native to Asia, this species is expanding its range throughout many parts of the globe. Here in Florida, it was first discovered in 1936. There was a bit of confusion surrounding its origin on this continent, however, it is now believed that seeds arrived in a shipment of centipede-grass from China.

Since its premiere in Florida, the lawn orchid has since spread to Georgia, Alabama, and Texas. It seems to be quite tenacious, growing equally as well in lawns, floodplains, forests, meadows, and even sidewalk cracks! Despite this generalist habit, it does not seem to transplant well and is probably quite specific about its mycorrhizal partner. Much work needs to be done to sleuth out exactly why this little orchid has been able to spread so far outside of its native range.

Though small flies will visit the flowers, it is very likely that this orchid mostly self pollinates. It doesn't take long to flower and set seed. One plant can easily result in hundreds if not thousands of seedlings. After setting seed, the parent plant dies, however, it will often bud off new plantlets from its roots. Its ubiquitous nature can often stand in contrast to its ability to disappear for a series of time. Large stands that appear one year may not return for many years after. Still, in some areas this little orchid is abundant enough to be considered a nuisance.

Despite whatever feelings you may have towards this little plant, I nonetheless admire it. Its not often you find orchids so adaptable to a wide variety of conditions. At the very least it offers us insights into the success of plant invasions around the globe. And, in the end, its a nice looking little plant.

Further Reading: [1] [2]

Important Lessons From Ascension Island

Located in the middle of the South Atlantic, Ascension Island is probably not on the top of anyone's travel list. This bleak volcanic island doesn't have much to offer the casual tourist but what it lacks in amenities it makes up for in a rich and bizarre history. Situated about 2,200 km east of Brazil and 3,200 km west of Angola, this remote island is home to one of the most remarkable ecological experiments that is rarely talked about. The roots of this experiment stem back to a peculiar time in history and the results have so much to teach the human species about botany, climate, extinction, speciation, and much more. What follows is not a complete story; far from it actually. However, my hope is that you can take away some lessons from this and, at the very least, use it as a jumping off point for future discussions. 

Ascension Island is, as land masses go, quite young. It arose from the ocean floor a mere 1 million years ago and is the result of intense volcanic activity. Estimates suggest that volcanism was still shaping this island as little as 1000 years ago. Its volcanic birth, young age, isolated conditions, and nearly non-existent soils meant that for most of its existence, Ascension Island was a depauperate place. It was essentially a desert island. Early sailors saw it as little more than a stopover point to gather turtles and birds to eat as they sailed on to other regions. It wasn't until 1815 that any permanent settlements were erected on Ascension. 

Photo by Drew Avery licensed under CC BY 2.0

In looking for an inescapable place to imprison Napoleon Bonaparte, the Royal Navy claimed Ascension in the name of King George III. Because Napoleon had a penchant for being an escape artist, the British decided to build a garrison on the island in order to make sure Napoleon would not be rescued. In doing so, the limitations of the island quickly became apparent. There were scant soils in which to grow vegetables and fresh water was nearly nonexistent. 

The native flora of Ascension was minimal. It is estimated that, until the island was settled, only about 25 to 30 plant species grew on the island. Of those 10 (2 grasses, 2 shrubs, and 6 ferns) were considered endemic. If the garrison was to persist, something had to be done. Thus, the Green Mountain garden was established. British marines planted this garden at an elevation of roughly 2000 feet. Here the thin soils supported a handful of different fruits and vegetables. In 1836, Ascension was visited by a man named Charles Darwin. Darwin took note of the farm that had developed and, although he admired the work that was done in making Ascension "livable" he also noted that the island was "destitute of trees."

One of Ascension Island's endemic ferns - Pteris adscensionis. Photo by Drew Avery licensed under CC BY 2.0

Others shared Darwin's sentiment. The prevailing view of this time period was that any land owned by the British empire must be transformed to support people. Thus, the wheels of 'progress' turned ever forward. Not long after Darwin's visit, a botanist by the name of Joseph Hooker paid a visit to Ascension. Hooker, who was a fan of Darwin's work, shared his sentiments on the paucity of vegetation on the island. Hooker was able to convince the British navy that vegetating the island would capture rain and improve the soil. With the support of Kew Gardens, this is exactly what happened. Thus began the terraforming of Green Mountain.

Photo by LordHarris licensed under CC BY-SA 3.0

For about a decade, Kew shipped something to the tune of 330 different species of plants to be planted on Ascension Island. The plants were specifically chosen to withstand the harsh conditions of life on this volcanic desert in the middle of the South Atlantic. It is estimated that 5,000 trees were planted on the island between 1860 and 1870. Most of these species came from places like Argentina and South Africa. Soon, more plants and seeds from botanical gardens in London and Cape Town were added to the mix. The most incredible terraforming experiment in the world was underway on this tiny volcanic rock. 

By the late 1870's it was clear the the experiment was working. Trees like Norfolk pines (Araucaria heterophylla), Eucalyptus spp. and figs (Ficus spp.), as well as different species of banana and bamboo had established themselves along the slopes of Green Mountain. Where there was once little more than a few species of grass, there was now the start of a lush cloud forest. The vegetation community wasn't the only thing that started to change on Ascension. Along with it changed the climate. 

Photo by Drew Avery licensed under CC BY 2.0

Estimates of rainfall prior to these terraforming efforts are sparse at best. What we have to go on are anecdotes and notes written down by early sailors and visitors. These reports, however, paint a picture of astounding change. Before terraforming began, it was said that few if any clouds ever passed overhead and rain rarely fell. Those living on the island during the decade or so of planting attested to the fact that as vegetation began to establish, the climate of the island began to change. One of the greatest changes was the rain. Settlers on the island noticed that rain storms were becoming more frequent. Also, as one captain noted "seldom more than a day passes over now without a shower or mist on the mountain." The development of forests on Ascension were causing a shift in the island's water cycle. 

Plants are essentially living straws. Water taken up by the roots travels through their tissues eventually evaporating from their leaves. The increase in plant life on the island was putting more moisture into the air. The humid microclimate of the forest understory cooled the surrounding landscape. Water that would once have evaporated was now lingering. Pools were beginning to form as developed soils retained additional moisture.

Photo by Ben Tullis licensed under CC BY 2.0

Now, if you are anything like me, at this point you must be thinking to yourself "but what about the native flora?!" You have every right to be concerned. I don't want to paint the picture that everything was fine and dandy on Ascension Island. It wasn't. Even before the terraforming experiment began, humans and other trespassers left their mark on the local biota. With humans inevitably comes animals like goats, donkeys, pigs, and rats. These voracious mammals went to work on the local vegetation. The early ecology that was starting to develop on Ascension was rocked by these animals. Things were only made worse when the planting began.

Of the 10 endemic plants native to Ascension Island, 3 went extinct, having been pushed out by all of the now invasive plant species brought to the island. Another endemic, the Ascension Island parsley fern (Anogramma ascensionis) was thought to be extinct until four plants were discovered in 2010. The native flora of Ascension island was, for the most part, marginalized by the introduction of so many invasive species. This fact was not lost of Joseph Hooker. He eventually came to regret his ignorance to the impacts terraforming would have on the native vegetation stating “The consequences to the native vegetation of the peak will, I fear, be fatal, and especially to the rich carpet of ferns that clothed the top of the mountain when I visited it." Still, some plants have adapted to life among their new neighbors. Many of the ferns that once grew terrestrially, can now be found growing epiphytically among the introduced trees on Green Mountain. 

The Ascension Island parsley fern (Anogramma ascensionis). Photo by Ascension Island Government Conservation Department licensed under CC BY-SA 3.0

Today Ascension Island exists as a quandary for conservation ecologists. On the one hand the effort to protect and conserve the native flora and fauna of the island is of top priority. On the other hand, the existence of possibly the greatest terraforming effort in the world begs for ecological research and understanding. A balance must be sought if both goals are to be met. Much effort is being put forth to control invasive vegetation that is getting out of hand. For instance, the relatively recent introduction of a type of mesquite called the Mexican thorn (Prosopis juliflora) threatens the breeding habitat of the green sea turtle. Efforts to remove this aggressive species are now underway. Although it is far too late to reverse what has been done to Ascension Island, it nonetheless offers us something else that may be more important in the long run: perspective.

If anything, Ascension Island stands as a perfect example of the role plants play in regulating climate. The introduction of these 330+ plant species to Ascension Island and the subsequent development of a forest was enough to completely change the weather of that region. Where there was once a volcanic desert there is a now a cloud forest. With that forest came clouds and rain. If adding plants to an island can change the climate this much, imagine what the loss of plants from habitats around the world is doing. 

Each year an estimated 18 million acres of forest are lost from this planet. As human populations continue to rise, that number is only going to get bigger. It is woefully ignorant to assume that habitat destruction isn't having an influence on global climate. It is. Plants are habitat and when they go, so does pretty much everything else we hold near and dear (not to mention require for survival). If the story of Ascension does anything, I hope it serves as a reminder of the important role plants play in the function of the ecosystems of our planet. 

The endemic Ascension spurge (Euphorbia origanoides). Photo by Drew Avery licensed under CC BY 2.0

Photo by DCSL licensed under CC BY-NC 2.0

Photo Credits: [1] [2] [3] [4] [5] [6] [7] [8]

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

A Cave Dwelling Nettle From China

Photo by Monro & Wei [SOURCE]

Caves and plants do not seem like a good combo. Plants need sunlight and caves offer very little to none of it. However, plants in general never seem to read the literature we write about them. As such, they are constantly surprising botanists all over the world. 

A recent example of this was published back in September of 2012. A team of botanists exploring limestone gorges in southwestern China stumbled upon three new members of the nettle family. One of these nettles seemed to be right at home growing well within two limestone caves. 

Needless to say this was quite a shock to the botanists. The regions in which these plants were growing were quite dim, with light levels ranging from a mere 0.04% to a measly 2.78 % of full daylight! Although this is by no means complete darkness, it is an incredibly low amount of sunlight for a plant that still relies on photosynthesis to get by. 

They named the nettle Pilea cavernicola in reference to its cave-dwelling habit. While it has only just been discovered, the IUCN considers this species vulnerable. Only two populations are known and their proximity to expanding human activity puts them in danger of rapid extinction. 

Photo Credit: Monro & Wei

Further Reading: [1]

High Elevation Record Breakers Are Evidence of Climate Change

[SOURCE]

A new record has been set for vascular plants. Three mustards, two composits, and a grass have been found growing at an elevation of 20,177 feet (6,150 m) above sea level!

Mountains are a brutal place to live. Freezing temperatures, fierce winds, limited soil, and punishing UV radiation are serious hurdles for any form of life. Whereas algae and mosses can often eke out an existence at such altitudes, more derived forms of life have largely been excluded from such habitats. That is, until now. The area in which these plants were discovered measured about the size of a football field and is situated atop an Indian mountain known as Mount Shukule II.

Although stressed, these plants were nonetheless established among the scree of this menacing peak. Most were quite young, having only been there for a few seasons but growth rings on the roots of at least one plant indicated that it had been growing there for nearly 20 years!

All of them have taken the cushion-like growth habit of most high elevation plant species in order to reduce exposure and conserve water. The leaves of each species also contained high levels of sugary anti-freeze, a must in this bitter cold habitat.

The research team, who could only muster a few hours of work each day, believed that the seeds of these plants were blown up there by wind. Because soils in alpine zones are often non-existent, the team wanted to take a closer look at what kind of microbial community, if any, was associated with their roots.

Whereas no mycorrhizal species were identified, the team did find a complex community of bacteria living among the roots that are characteristic of species living in arid, desert-like regions. It is likely that these bacteria came in with the seeds. Aside from wind, sun, and a lack of soil, one of the other great challenges for these plants is a short growing season. In order to persist at this elevation, the plants require a minimum of 40 days of frost-free soil each year.

Because climate change is happening much faster in mountainous regions, it is likely that such favorable growing conditions are a relatively recent phenomenon. The area in question has only recently become deglaciated. As average yearly temperatures continue to increase, the habitable zone for plants such as these is also moving up the mountain. The question is, what happens when it reaches the top? Once at the peak, plants have nowhere to go. One of the greatest issues alpine plants face is that they will gradually be squeezed off of these habitat islands.

Although expanding habitable zones in these mountains may sound like a good thing, it is likely a short term benefit for most species. Whereas temperature bands in the Tibetan mountains are moving upwards at a rate of 20 feet (6 m) per year, most alpine plants can only track favorable climates at a rate of about 2 inches (0.06 m) per year. In other words, they simply can't keep up. As such, this record breaking discovery is somewhat bitter sweet.

Photo Credit: [1]

Further Reading: [1]

Catnip and Cats

Photo by Wylie licensed under CC BY 2.0

We have all seen a cat in the throes of a catnip high. Rolling around, salivating, vocalizing, these are just some of the ways in which cats respond to contact with this drug-like substance. It is strange to think that a plant could elicit such strong reactions from our feline companions. What is is about this plant that causes cats to go crazy?

Let's back up for a second. To start with, catnip is the dried, crushed leaves of mints in the genus Nepeta. Commonly referred to as catmints, these plants are native to parts of Europe and Asia, though they have been introduced throughout the globe and tend to favor waste places and fields. The main source of catnip comes from Nepeta cataria. Though not a showy plant, it certainly has gained traction throughout the gardening world.

Nepeta cataria is often used as a companion plant by those growing vegetables. It is used to deter insect pests like aphids and squash bugs. Because of this, it is often used as a natural mosquito repellent as well, though research has shown that, at least on human skin, it is not very effective. Like all mints, the volatile compounds that give them their scent are what interests humans the most. One of these compounds, specifically a terpenoid called nepetalactone, is also what drives cats a bit crazy.

It has long been noted that cats are attracted to the bruised leaves of Nepeta cataria. Not all cats respond to catnip though. In fact, sensitivity to catnip is hereditary and is only present in about 70 to 80% of felines. It's not just domestic cats either. Wild cats like tigers and leopards have also shown sensitivity to this chemical. When nepetalactone enters the nasal cavity of a cat, it attaches to special protein receptors, which stimulates sensory neurons.

Through a complex chain of reactions, the hypothalamus responds by stimulating the pituitary gland, which creates a sexual response in the cats brain. In essence, nepetalactone acts as a synthetic cat pheromone. Essentially it makes cats kind of horny. The effects of nepetalactone last for about 10 minutes, after which the cat becomes desensitized for about 30 minutes. Interestingly enough, nepetalactone is also found in the wood of tartarian honeysuckle (Lonicera tatarica), which is also used in cat toys.

Photo Credit: [1]

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

The Fuzziest of Flowers

Photo by Andreas Kay licensed under CC BY-NC-SA 2.0

Describing plants can be quite a task for taxonomists. When a new species is discovered, the honor of naming it often goes to the discoverer. At the very least, they have some input. Some folks go for the more traditional rout and give the plant a descriptive name rooted in either Latin or Greek. Others decide to name the plant in honor of a botanist of the past or perhaps a loved one. Still others take a stranger approach in order to immortalize a famous celebrity. However, in doing so they risk taking something away from the species in question.

Instead of a descriptive name that clues you in on specific features of the plant, instead you hit an etymological dead end in which you are stuck with nothing more than a last name. This became quite apparent to University of Alabama botanist John Clark when it was time to name a newly discovered plant species from South America. 

Had things been slightly different, the recently discovered Kohleria hypertrichosa would have been named after Chewbacca. One look at the flowers of this species and you can understand why. The long tubular petals of this gesneriad are covered in dense, fuzzy hair. This is unlike any other plant known to science. The appearance of these odd fuzz balls may seem puzzling at first but considering where this plant was found growing, it quickly becomes apparent that these flowers are a marvelous adaptation in response to climate. 

Kohleria hypertrichosa is only known to grow in a very narrow swath of mountainous cloud forest in the Ecuadorian Andes. At home between elevations of 3,600 and 6,600 feet above sea level, this wonderful gesneriad experiences some pretty low temperatures for a tropical region. It is likely that the thick layer of hairs keeps the flowers a bit warmer than the surrounding air, offering a welcoming microclimate for pollinators. This could potentially make them much more likely to be pollinated in a habitat where pollinators may be in short supply. 

At the end of the day, Clark decided to stick with a more traditional name for this new species. Its scientific name is no less interesting as a result. The specific epithet 'hypertrichosa' is derived from a condition in humans known as hypertrichosis, or werewolf syndrome, in which a person grows excessive amounts of body hair. 

Photo Credit: Andreas Kay [1]

Further Reading: [1]

The Curious Case of a Dancing Plant

Plants aren't generally known for their speed. They tend to move at rates we simply can't perceive. The few species that exhibit rapid movements such as the sensitive plant (Mimosa pudica) and the Venus fly trap (Dionaea muscipula) have become quite famous as a result. Such movements happen in fits and bursts. These plants certainly cannot maintain such activity. However, there is another plant out there whose activity puts these other plants to shame.

Meet the telegraph plant. It has gone by a handful of scientific names since its discovery (Desmodium motorium, D. gyrans, Hedysarum gyrans, Codariocalyx motorius) but that's not why its famous. This Asian legume is renown for its maneuvers. Its compound leaves are surprisingly active organs. The larger terminal leaflets move up and down throughout the course of a day but its smaller lateral leaflets exhibit rhythmic movements on the scale of minutes.

Perhaps most famously, the leaflets show an increase in movement when exposed to music. Search the web and you will find lots of videos of the telegraph plant "dancing" to a variety of musical styles. Though entertaining, music is not why this plant moves. Having evolved long before music was ever invented, its movement must have its roots in something a bit more natural. However, despite how popular such motion has made this species over the past few centuries, their its function has remained a bit of a mystery.

Before we get into the theories, let's take a closer look at exactly how this plant moves. At the base of its leaflets there sits a ring of cells called the "pulvinus." They act a bit like water balloons and thanks to some dedicated work, it has been found that, when stimulated, these cells can quickly move water in and out via osmosis. This causes the cells to either swell or deflate and this is where the movement originates. Now, onto the why...

A relatively recent opinion piece puts forth some of the most interesting theories on telegraph plant movement yet. The author suggests that leaflet movements are defensive in nature. They believe that the leaves could be mimicking butterfly (or some other winged arthropod movements). In doing so, it may convince gravid female insects that this individual plant is already occupied. Such strategies do indeed exist in some plant species, though via physical adornments rather than movements. Another theory this author puts forth is that their movements could also attract potential predators. By mimicking the movement of a tasty insect, it could entice birds to come in to take a closer look. Once there, they could easily find other herbivores hiding on the plant.

Another possibility related to defense is that the movements are meant to deter herbivory altogether. Studies on other plants have shown that some species can actually detect the vibrations of an insect chewing on leaves, which signals to the plant to uptick the production of defense compounds. Perhaps when sensing vibration, the telegraph plant increases its movements to knock away a hungry insect. Certainly a moving meal is less appealing than a stationary one. This is also thought to be the reason for rapid leaflet closure in sensitive plants. Hungry insects have a hard time hanging on to a plant when the leaf suddenly collapses from underneath it.

Another hypothesis is that these movements are meant to increase sun exposure. It has been discovered that far from only responding to music, the leaflets move throughout the day depending on temperature. When temperatures are low, leaflet movements are more vigorous. They eventually slow down if temperatures are high enough. This hypothesis is bolstered by the fact that movements cease once the sun goes down. In a sense, the leaflets seem to be using temperature as a means of detecting whether or not they are getting as much sun on them as possible.

In reality, it very well could be a mix of these ideas. Natural selection works like that. In the end, movement of the leaflets has certainly benefited the telegraph plant whether it be fore defense or just to take advantage of as much sun as possible. Despite centuries of popularity, this awesome little legume still has some secrets tucked away and I kind of like that about it.

NOTE: The image at the top of this page is of a time lapse and does not represent actual speed.

Photo Credit: [1]

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

Wasabi

Photo by Qwert1234 licensed under CC BY-SA 3.0

Whether you like wasabi or hate it, there is a very high probability that you have never actually tasted it. It is estimated that only about 5% of Japanese restaurants around the world actually offer the real stuff. Instead, the wasabi we most often indulge in is a mix of mustard, European horseradish (Armoracia rusticana), and green food coloring. This begs the question, why is real wasabi so hard to come by?

The answer to this lies in the plant. Real wasabi comes from a species of mustard native to the mountains of Japan. Flowering for this group consists of an inflorescence packed with small, white, 4-petaled flowers shoots up above the leaves. There exists two species within the genus - the uncultivated Wasabia tenuis and the cultivated Wasabia japonica. It has been suggested that these plants be moved out of the genus Wasabia and into the genus Eutrema. Regardless of their taxonomic affiliation, these are beautiful and interesting plants. 

Whereas W. tenuis tends to grow on mesic mountainsides, W. japonica prefers to grow in and around streams. In fact, it can often be found growing right out of the gravelly stream bed. Its strict riparian habit has made it hard for this plant to catch on commercially. Although it doesn't grow submerged like an aquatic plant, it nonetheless needs running water. Without it, the plant will languish and die. Although methods of soil growing W. japonica are sometimes used, these are very labor intensive and require a lot of inputs in order for the plants to thrive. The plant also seems to be highly susceptible to disease if planted in high densities. Overall this has made finding real wasabi a difficult, and not to mention expensive, venture. 

Photo Credit: Qwert1234 (Wikimedia Commons)

Further Reading: [1]

Staying Warm: An Alpine Plant Approach to Reproduction

Photo by Richard Jones licensed under CC BY-NC-ND 2.0

Things are beginning to cool down throughout the northern hemisphere. As winter approaches, most plant species begin to enter their dormancy period. Very few plants risk wasting their reproductive efforts in the chill of late fall, having gotten most of it out of the way during the warm summer months. This is easy enough for low elevation (and low latitude) plants but what about species living in the high arctic or alpine habitats. Such habitats are faced with cold, harsh conditions year round. How do plants living in these zones deal with reproduction?

These limitations are overcome via physiology. For starters, plants living in such extreme habitats often self pollinate. Insects and other pollinators are too few and far between to rely solely upon them as a means of reproduction. Also, the flowers of most cold weather plants are heliocentric. This means that, as the sun moves across the sky, the flowers track its path so that they are constantly perpendicular to its rays. This maintains maximum exposure to this precious heat source. 

Additionally, many arctic and alpine plants have parabolically shaped flowers. This amplifies the incoming radiation being absorbed by the flower. Experiments have shown that flowers that have been shaded from the heat of the sun had a dismal seed set of only 8% whereas plants exposed to the sun had an elevated seed set of 60%. 

For plants in these habitats, its all about persistence. Low reproductive rates are often offset by extremes in longevity. This is one of the many reasons why hikers must remember to tread lightly in these habitats. Damages incurred by even a single careless hiker can take decades, if not centuries, to recover. 

Photo Credit: [1]

Further Reading: [1]

Plants and Music

Turn up the music! My plants can't hear it! Okay, there goes a cheap attempt at humor... In all seriousness, I was always told as a child that plants respond to music. I have since heard many variations on the theme but basically the ideas is that plants, when exposed to music, respond with increased growth. To take things one step further, it would seem that plants have something akin to musical tastes, preferring classical to rock music.

Is there any real scientific evidence to this or is it all just a bunch of silly pseudoscience? Also, if it is true, what could possibly be going on within the plant that causes a response to music, something we thought was reserved to lifeforms with the proper sensory equipment?

The truth is, there is not much real science to base these assumptions on. The internet is full of anecdotal tales and "experiments" that hinge themselves on new age belief systems. In fact, the first "experiments" on how music influences plant growth was done by a woman named Dorothy Retallack. 

Retallack claimed that plants exposed to classical music grew vigorously whereas plants exposed to rock music languished. Considering how much heavy metal my houseplants are exposed to, I think I have more than enough evidence to say otherwise. Besides her poor experimental design, Retallack was heavily motived by quite a conservative, religious agenda. She had it out for mean old rock n' roll and was damned if she couldn't prove her point. What work has been done since Rettalack's time is tantalizing at best but from this point on, keep in mind that the jury is still out on this topic.

So, why would plants respond to music? They don't have ears or anything in their biology that would function as an auditory device, right? Let's re-frame the question in a more basic sense. What is music? Music is nothing more than organized sounds and sounds are nothing more than pressure waves, that is, disturbances in the atmosphere, a process akin to wind. Plants do, in fact, respond to wind, however, wind is a far more physical force than music. Wind can blow over entire swaths of forest whereas music cannot. What mechanism exists that could possibly explain a plant having any kind of response to music? 

Plants respond to heavy wind by growing smaller or by hugging the ground (think alpine vegetation). High winds could generally be seen as a taxing force in the plant world so why would music make plants grow taller and more vigorous? In my opinion, this idea is not a satisfying explanation. As stated above, music doesn't come close to the raw physical power of wind so there could be something else at work. 

In a study done by Margaret E. Collins and John E.K. Foreman out of the University of Western Ontario in London, Canada, they demonstrated that plants responded to different kinds of tones. The tones were either pure (without variation) or random. The results did not show any sort of negative responses from the plants, but rather the plants showed different rates of growth. Plants exposed to pure tones grew better than those exposed to random tones. 

The mechanism they hypothesized for the increased growth in pure tone plants was that the pure tones were able to move air, however slightly, around the leaf. Plants don't like stagnant air and thus, slight air movement is likely to be more beneficial. The random tones did not produce as vigorous of a response, but the plants still grew. It is possible that the random tones caused less air movement around the plants and, because of this, they did not grow as quickly.

Another explanation that seems plausible was put forth by USCB via their science line. They feel that one possible explanation is that the plants aren't the ones responding to the music, but rather the gardener. If you are listening to music while caring for your plants, then chances are it is music you enjoy. If you are like me, then music really has the power to put you in a good mood. If you are in a good mood then chances are you are more likely to take better care of your plants.

All in all, this is an interesting idea. As I said above, the results are mostly controversial and new agey. There are some tantalizing papers that have been published but their methods have been heavily scrutinized. It seems like this is one of the more popular science fair projects for kids to explore and really, anything that gets kids thinking about science and plants is a cool idea in my book. Until more hard science is done on the subject, we can't say for certain. Either way, I will continue to rock out to my favorite tunes and maybe, just maybe, my plants are benefiting from it too.

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

Bacteria Help the Cobra Lily Subdue Prey

Photo by David Berry licensed under CC BY 2.0

The cobra lily (Darlingtonia californica) is one of North America's most stunning pitcher plants. Native to a small region between northern California and southwestern Oregon, this bizarrely beautiful carnivore lives out its life in nutrient poor, cold water bogs and seeps. Although it resides in the same family as our other North American pitcher plants, Sarraceniaceae, the cobra lily has a unique taxonomic position as the only member of its genus.

It doesn't take much familiarity with this plant to guess that it is carnivorous. Its highly modified leaves function as superb insect traps. Lured in by the brightly colored, tongue-like protrusions near the front tip of the hood, insects find a sweet surprise. These tongue-like structures secrete nectar. As insects gradually make their way up the tongue, they inevitably find themselves within the downward pointing mouth of the pitcher. This is where those translucent spots on the top of the hood come in.

Those translucent spots trick the insects into flying upwards into the light. Instead of a clean getaway, insects crash into the inside of the hood and fall down within the trap. The slippery walls of the pitcher interior make escape nearly impossible but that isn't the only thing keeping insects inside. Research has shown that the cobra lily gets a helping hand from bacteria living within the pitcher fluid.

Unlike other pitcher plants, the cobra lily does not fill its traps with rain water. The downward pointing mouth prevents that from happening. Instead, the pitchers secrete their own fluid by pumping water up from the roots. Although there is evidence that the cobra lily does produce at least some of its own digestive enzymes, it is largely believed that this species relies heavily on a robust microbial community living within its pitchers to do most of the digesting for it. This mutualistic community of microbes saves the plant a lot of energy while also providing it with essential nutrients like nitrogen in return for a safe place to live.

That isn't all the bacteria are doing for this pitcher plant either. As it turns out, the pitchers' microbial community may also be helping the plant capture and subdue its prey. A study based out of UC Berkeley demonstrated that the presence of these microbes helps lower the surface tension of the water, effectively drowning any insect almost immediately.

Some members of the microbial community release special compounds called biosurfactants. Through an interesting chemical/physical process that I won't go into here, this keeps insects from using the surface tension of the water to keep them afloat, not unlike a water strider on a pond. Instead, as soon as insects hit the bacteria infested waters, they break the surface tension and sink down to the bottom of the pitcher where they quickly drown. There is little chance of escape for a hapless insect unlucky enough to fall into a cobra lily trap.

Although plant-microbe interactions are nothing new to science, this example is the first of its kind. Although this prey capture role is very likely a secondary benefit of the microbial community within the pitchers, it certainly makes a big difference for these carnivores living in such nutrient poor conditions.

Read more about the amazing world of carnivorous plants by picking up a copy of my book!

Photo Credit: [1] [2]

Further Reading: [1]

A Green Daffodil From Spain

Photo by A. Barra licensed under CC BY 3.0

There are some plants that are so ubiquitous in horticulture that I almost forget that they have wild constituents. Every plant in our gardens can trace its lineage back to the wild. As is often the case, I find the wild congeners of our most beloved horticultural curiosities to be far more fascinating. Take, for instance, the genus Narcissus. Who doesn't recognize a daffodil? The same cannot be said for their wild cousins. In fact, there exists some pretty fantastic species within this genus including a small handful of species that flower in autumn. 

A unique fall flowering daffodil is a species known scientifically as Narcissus viridiflorus. This lovely little plant is quite restricted in its range. You will only find it growing naturally in a small region around Gibraltar where it is restricted to rich, clay and/or rocky soils. During years when it is not in flower, N. viridiflorus produces spindly, rush-like leaves. As such, it can be hard to find. 
 

When Narcissus viridiflorus does decide to flower, it forgoes leaf production. From the bulb arises a single green scape. From that scape emerges the flower. The flowers of this bizarre daffodil are decidedly not very daffodil-like. They are rather reduced in form, with long, slender green petals and a nearly nonexistent daffodil cone. Also, they are green. Though I have not seen this investigated directly, it has been suggested that the green scape and flowers contain enough chlorophyll that they plant can recoup at least some of the energy involved in producing flowers and eventually seed. 

The flowers themselves open at night and are said to be very fragrant. Again, no data exists on who exactly pollinates this species but the timing, color, and smell all suggest nocturnal insects like moths. Like the other daffodils of this region, Narcissus viridiflorus is poorly understood. Taken in combination with its limited distribution one can easily see how such a species may be quite vulnerable to human disturbance. As it stands now, this species and many of its cousins are no more than horticultural curiosities for more niche bulb societies. In other words, Narcissus viridiflorus is in need of some real attention. 

Photo Credit: [1] [2]

Further Reading: [1]

The Gas Plant

Photo by Jörg Hempel licensed under CC BY-SA 3.0 de

Meet the gas plant, Dictamnus albus. This lovely herbaceous species is native to southern Europe, north Africa, and Asia. The gas plant is a member of the citrus family, Rutaceae, and like many members of this group, it has very showy blossoms. Its affiliation with the citrus fruits on your counter isn't the only interesting thing about this species. As the common name might suggest, this plant does something quite strange. 

During the heat of summer, parts of the gas plant exude an oily substance that smells much like the fruits of its cousin, the lemon. These oils have been known to cause contact dermatitis not unlike the sap of giant hogweed. However, this is not the strangest aspect of the gas plants oily nature. One of the properties of these oils is that they are highly volatile. So volatile in fact that they can ignite. 

Another common name for this species is burning bush (though not the one of biblical lore). If air temperatures get high enough or if someone takes a match to this plant on a hot day, the oils covering its tissues will ignite in a flash. The oils burn off so quickly that it is of no consequence to the plant. It goes on growing like nothing ever happened. If you're like me then you have one burning question after reading this - why?!

Despite how incredible this phenomenon may seem, it doesn't appear that too many people have looked into its function. Research has identified a highly flammable organic compound within the oils called isoprene. In plants, isoprenes are thought to protect against heat stress. This is bolstered by the fact that the gas plant produces these compounds during the heat of summer. 

Another possibility is that spontaneous ignition of these compounds could create small wildfires that clear the surrounding area of competition. I have not seen any evidence suggesting this. Yet another possibility is that this is simply an unrelated side effect of oil production. Since the plant is not hurt by the quick burst of flames, it simply hasn't had any reason to evolve a less flammable alternative. Evolution is funny like that. 

Still don't believe what you are reading? Check out this video:

Photo Credit: Jörg Hempel (Wikimedia Commons)

Further Reading: [1]

Lizard Helpers

Photo by Tatters ✾ licensed under CC BY-NC-ND 2.0

The beauty of Tasmania's honeybush, Richea scoparia, is equally matched by its hardiness. At home across alpine areas of this island, this stout Ericaceous shrub has to contend with cold temperatures and turbulent winds. The honeybush is superbly adapted to these conditions with its compact growth, and tough, pointy leaves. Even its flowers are primed for its environment. They emerge in dense spikes and are covered by a protective casing comprised of fused petals called a "calyptra." Such adaptations are great for protecting the plant and its valuable flowers from such brutal conditions but how does this plant manage pollination if its flowers are closed off to the rest of the world? The answer lies in a wonderful little lizard known as the snow skink (Niveoscincus microlepidotus).

The snow skink is not a pollinator. Far from it. All the snow skink wants is access to the energy rich nectar contained within the calyptra. In reality, the snow skink is a facilitator. You see, the calyptra may be very good at shielding the developing flower parts from harsh conditions, but it tends to get in the way of pollination. That is where the snow skink comes in. Attracted by the bright coloration and the nectar inside, the snow skink climbs up to the flower spike and starts eating the calyptra. In doing so, the plants reproductive structures are liberated from their protective sheath. 

Photo by Tindo2 - Tim Rudman licensed under CC BY-NC 2.0

Once removed, the flowers are visited by a wide array of insect pollinators. In fact, research shows that this is the only mechanism by which these plants can successfully outcross with their neighbors. Not only does the removal of the calyptra increase pollination for the honeybush, it also aids in seed dispersal. Experiments have shown that leaving the calyptra on resulted in no seed dispersal. The dried covering kept the seed capsules from opening. When calyptras are removed, upwards of 87% of seeds were released successfully. 

Although several lizard species have been identified as pollinators and seed dispersers, this is some of the first evidence of a reptilian pollination syndrome that doesn't actually involve a lizard in the act of pollination. It is kind of bizarre when you think about it. As if pollination wasn't strange enough in requiring a third party for sexual reproduction to occur, here is evidence of a fourth party required to facilitate the action in the first place. It may not be just snow skinks that are involved either. Evidence of birds removing the calyptra have also been documented. Whether its bird or lizard, this is nonetheless a fascinating coevolutionary relationship in response to cold alpine conditions. 

Photo Credits: [1] [2]

Further Reading: [1]

Rare African Plant Gets A Boost

Photo by chuck b. licensed under CC BY 2.0

The reappearance of the silver tree (Leucadendron argeteum) to the slopes of the Tokai Arboretum is so exciting. A member of the family Proteaceae, this beautifully bizarre plant was once common around Cape Town, South Africa. Sadly, their populations have declined by 74%. The cause of this decline is not surprising - deforestation, urbanization, fire sequestration, disease, and invasive species have all taken their toll on this species. With this recent discovery, however, there may be hope yet.

The plants were discovered by a team of volunteers while they were clearing the land of invasive tree cover. The seedlings were small but this species grows fast, up to 500 mm per year. A seedling today can quickly become a mature tree in only a few years. The key to their resurgence are their seeds. Silver tree seeds will not germinate under a closed canopy. Instead, they lie and wait in the soil for decades until fire clears the area of competing vegetation. Without fire, no new trees were growing in to replace dying adults. Hence the situation was looking bleak. 

The discovery of juvenile trees is worth celebrating. After a century of functioning as a pine plantation, this area just might be recovering some of its lost diversity. This species is not out of the woods yet. Experts estimate that it could take another 100 years of seed sowing and proper land management before this area can bolster a thriving silver tree population. Still, it stands as an important reminder that there is hope. Even the most degraded patches of land can hold on to their legacies. There are countless other species out there that, like the silver tree, are teetering on the edge of extinction just waiting for a dedicated group of experts and volunteers to invest time and energy.

Photo Credits: [1] [2]

Further Reading: [1]

The Benefits of Houseplants

I don't know about you, but I find indoor gardening to be just as satisfying and intellectually stimulating as any amount of outdoor gardening. Coming from a temperate climate, I don't think I would be able to survive the long winters if it were not for my houseplants. The benefits to keeping plants in the home as well as the office are numerous and range the spectrum from improving air quality to diminishing stress and aiding in healing.

Few would probably argue that a room with plants in it feels far more lived in and hospitable than an empty, sterile room. It makes sense. We evolved, like everything else on this planet, in a natural setting filled with seemingly endless varieties of different plant species. It should be no surprise that our minds would be more at ease the more natural any environment seems. Studies have shown that in an indoor work environment, offices that contained plants had statistically significant reductions in employee discomfort, stress, and an increase in their overall well being. It doesn't end at work either. Hospitals and other medical facilities also showed that overall well being improved both physically and mentally with their residents. In patients suffering from dementia, indoor plants are said to "stimulate residents’ senses, created positive emotions, and offered opportunity for rewarding activity."

Plants do so much more than just improve our moods and reduce stress, they also clean the air we breath. Many every-day household items off-gas some pretty nasty chemicals. Insulation, particle board, PVC and vinyl, carpets, flooring, even our own clothing, all of these things come with their own gaseous and particulate chemical cocktails. It has been shown time and time again that many species of commonly kept house plants help to remove these molecules from the home environment. Some species are better than others. For instance, spider plants (genus Chlorophytum), are exceptionally good at removing formaldehyde compounds in the air. A room full of plants also exhibits statistically significant reductions in particulate matter as well as a measurable increase in humidity levels.

Whether they make you feel at ease or because they clean the air you breath, having house plants is a good thing. There are many species that are available both in nurseries as well as online. Some of the best plants for the home are also the most sensibly priced. Get online and do some research. There are a lot of easy plants to care for out there if you don't necessarily have a green thumb.

Further Reading: [1] [2] [3] [4] [5] [6] [7]

Underwater Pollinators

[SOURCE]

Modern day aquatic plants are highly derived organisms. Similar to dolphins and whales, today's aquatic plants did not originate in their watery environment. Instead, they gradually evolved from land plants living close to the water's edge. One of the biggest challenges for fully aquatic plants involves pollination. Many species overcome this hurdle by thrusting their flowers up and out of the water where there are far more pollen vectors. Others rely on water currents and a little bit of chance. For aquatic plants whose flowers open under water, water pollination, or "hydrophily", has long been the only proposed mechanism. Surely aquatic animals could not be involved in aquatic pollination. Well, a newly published study on a species of seagrass known scientifically as Thalassia testudinum suggests otherwise.

Seagrasses are ecological cornerstones in marine environments. They form vast underwater meadows and are considered one of the world's most productive ecosystems. Most seagrasses are clonal. Because of this, sexual reproduction in this group has mostly been overlooked. However, they do produce flowers that are tucked down in among their leaves. The production of flowers coupled with a surprising amount of genetic diversity have led some researchers to take a closer look at their reproduction.

A team of researchers based out of the National Autonomous University of Mexico decided to look at potential pollen vectors in Thalassia testudinum, a dominant seagrass species throughout the Caribbean and western Atlantic regions. T. tetidinum is dioecious, producing male and female flowers are separate plants. Flowers open for short periods of time and males produce pollen in sticky, mucilaginous strands. The research team had noticed that a wonderfully diverse group of aquatic animals visit these flowers during the night and began to wonder if it was possible that at least some of these could be effective pollinators.

Photo by James St. John licensed under CC BY 2.0

The team was up against a bit of a challenge with this idea. A simple visit to a flower doesn't necessarily mean pollination has been achieved. To be an effective pollinator, an animal must a) visit both male and female flowers, b) carry pollen on their bodies, c) effectively transfer that pollen, and d) that pollen transfer must result in fertilization. To quantify all four steps, the team used a series of cameras, aquariums, and natural mesocosm experiments. What they discovered was truly remarkable.

Not only did a diverse array of marine invertebrates visit the flowers during the duration of the study, they also carried pollen, which stuck to their bodies thanks to the thick mucilage. What's more, that pollen was then deposited on the female flowers, which rake up these invertebrates with their tentacle-like stigmas. Finally, pollen deposited on female flowers did in fact result in fertilization. Taken together, these data clearly demonstrate that animal pollinators do in fact exist in aquatic environments. It is likely that these invertebrates are most effective during periods when water movement is minimized. Water currents likely still make up a significant portion of the pollen transfer between individual plants. Still, this evidence changes the paradigm of aquatic pollination in a big way.

Photo Credits: [1] [2]

Further Reading: [1]

Shade Gives This Begonia the Iridescent Blues

Believe it or not, the blue iridescence of Begonia pavonina is an evolutionary adaptation to extracting the most amount of energy out of the dim light that makes it through the thick rainforest canopy above. Even more bizarre, it works thanks to an interesting property of quantum mechanics. 

Native to Malaysia, B. pavonina lives out its life in deep shade. Most of the sunlight that hits this region is absorbed by the thick canopy of trees above. As such, eking out an existence is a challenge for these understory herbs. That is where this fantastic blue iridescence comes in. To understand it better, researchers had to take a closer look at its cause. 

Inside any photosynthetic leaves resides the chloroplasts. Chloroplasts are filled with tiny stacks of membranous compartments called "thylakoids." This is where the light reactions of photosynthesis take place. Now, in most plants, these thylakoids are haphazardly distributed throughout the chloroplast. This is not the case for B. pavonina. For this species, the thylakoids are arranged in a very precise way.

It is this precision that gives the leaves their iridescent color. Their placement causes blue wavelengths of light to be reflected. This isn't a big loss for the plant as most of the blue light is absorbed by the canopy above anyway. What it does instead is quite fascinating. The stacked thylakoids act like a dense crystal. When light enters the chloroplasts of B. pavonina it is physically slowed down.

This effect is known to quantum physicists as "slow light." Whereas light traveling through a vacuum maintains a constant speed, light passing through different types of matter can actually be slowed down. By slowing light as it passes through the chloroplasts, the thylakoids are able to take advantage of what little light the leaves are able to intercept. For B. pavonina, this equates to a 10% increase in photosynthetic rates. Coupled with an increase in the absorbance of red-green light, one can understand why this is such an advantage. 

Another interesting aspect of its physiology is the fact that B. pavonina produces both "normal" and iridescent chloroplasts. It is thought that this is a form of backup for the plant. In instances where enough light actually does make it through to the forest floor, B. pavonina can use its normal chloroplasts instead. It should be noted that this is not the only case of blue iridescent leaves in the plant kingdom. Many other species including spike mosses, ferns, and even orchids exhibit this trait. Even leaves that don't appear iridescent to our eyes may be utilizing nanostructures such as those seen in B. pavonina to increase their photosynthetic efficiency in low light conditions. It is very likely that many different kinds of plants are physically manipulating light to their benefit.

Photo Credit: Michael Perry

Further Reading:

[1]

Evolving For City Life

Photo by Stefan.lefnaer licensed under CC BY-SA 4.0

Urban environments pose unique challenges to any plant. Cities are generally warmer, have significantly higher CO2 levels, and experience altered levels of disturbance and precipitation patterns than do rural areas nearby. Still, many plants have taken to these concrete jungles, popping up wherever they can eke out an existence. Although we are not reinventing ecological principals in urban areas, they nonetheless present distinct selective pressures on every living thing within their jurisdiction. Evidence now suggests that urban environments are actually shaping the evolution of at least some plant species. 

Motivated by a desire to better understand how urban conditions are influencing evolution, a team of researchers based out of the University of Minnesota decided to take a closer look at a common mustard called Virginia pepperweed (Lepidium virginicum). This hardy little annual is at home wherever disturbance occurs. As such, it can be found throughout most of North America and beyond. Because it self pollinates readily, researchers were able to quantify phenotypic differences between populations growing in dense urban centers and compare them to those growing in more rural areas.

Photo by Stefan.lefnaer licensed under CC BY-SA 4.0

They collected seeds from numerous urban and rural populations and grew them together in a greenhouse experiment. By exposing each population to the same conditions in the greenhouse, the team were able to tease out the true phenotypic differences between these populations. 

What their data revealed were distinct differences between urban and rural populations. For starters, urban plants had larger rosettes but fewer leaves. They also bolted sooner than rural plants but then exhibited a much longer period of time between bolting and flowers. Previous studies have shown that the inflorescence of related species "accounted for 55% of a plants photosynthetic activity but only 25% of water loss." Coupled with the reduction in the number of leaves, these results suggest that urban plants are maximizing photosynthesis under drier conditions. 

Another interesting difference is that urban plants produced far more seed than their rural counterparts. This very well may be due to the fact that urban plants tended to be larger. This could also be due to reduced herbivory in urban environments, though such pressures may vary from city to city. Due to the urban heat island effect, it is likely that this could be a result of more stable temperature conditions than those experienced by their rural counterparts. Taken together, these results show that there is indeed selection for traits that allow plants to not only survive but thrive in urban environments.

Photo Credit: Wikimedia Commons

Further Reading: [1]

Newly Discovered Orchid Doesn't Bother With Photosynthesis or Opening Its Flowers

Photo by Suetsugu Kenji [SOURCE]

A new species of orchid has been discovered on the small Japanese island of Kuroshima. Though not readily recognized as an orchid, it nonetheless resides in the tribe Epidendroideae. Although the flowers of its cousins are often quite showy, this orchid produces small brown blooms that never open. What's more, it has evolved a completely parasitic lifestyle. 

The discovery of this species is quite exciting. The flora of Japan has long thought to be well picked over by botanists and ecologists alike. Finding something new is a special event. The discovery was made by Suetsugu Kenji, associate professor at the Kobe University Graduate School of Science. This discovery was made about a year after a previous parasitic plant discovery made on another Japanese island a mere stones throw from Kuroshima.

Coined Gastrodia kuroshimensis, this interesting little parasite flies in the face of what we generally think of when we think of orchids. It is small, drab, and lives out its entire life on the shaded forest floor. Like the rest of its genus, G. kuroshimensis is mycoheterotrophic. It produces no leaves or chlorophyll, living its entire life as a parasite on mycorrhizal fungi underground. This is not necessarily bizarre behavior for orchids (and plants in general). Many different species have adopted this strategy. What was surprising about its discovery is the fact that its flowers never seem to open. 

In botany this is called "cleistogamy." It is largely believed that cleistogamy evolved as both an energy saving and survival strategy. Instead of dumping lots of energy into producing large, showy flowers to attract pollinators, that energy can instead be used for seed production and persistence. Additionally, since the flowers never open, cross pollination cannot occur. The resulting offspring share 100% of their genes with the parent plant. Although this can be seen as a disadvantage, it can also be an advantage when conditions are tough. If the parent plant is adapted to the specific conditions in which it grows, giving 100% of its genes to its offspring means that they too will be wonderfully adapted to the conditions they are born into. 

As you can probably imagine, pure cleistogamy can be quite risky if conditions rapidly change. In the face of continued human pressures and rapid climate change, cleistogamy as a strategy might not be so good. That is one reason why the discovery of this bizarre little orchid is so interesting. Whereas most species that produce cleistogamous flowers also produce "normal" flowesr that open, this species seems to have given up that ability. Thus, G. kuroshimensis offers researchers a window into how and why this reproductive strategy evolved. 

Photo Credit: Suetsugu Kenji

Further Reading: [1]