Pseudoanthry

I learned a new word today - "pseudoanthery." This term applies to a structure or organ on a nectarless flower that mimics a dehiscent anther. To elaborate further, a dehiscent anther is one in which a capsule containing pollen breaks open to reveal the pollen inside. For example, think of the anthers of an Asiatic lily. Back to the topic at hand.

I quite like learning new things, especially as it applies to familiar friends. I was admiring the floral display of a rather tall cane begonia when a friend of mine came up to me and simply said "pseudoanthery." I didn't quite catch it the first time so I asked him to repeat it. It wasn't hard to guess the root meaning of the word - fake anther. Confusion set in when I pointed out that I was looking at the female flowers of a begonia. Thus, a teaching moment presented itself.

Though I adore Begonias and have a small handful growing in my house at all times, I never stopped to think much about their pollination. Without a doubt, they can be quite showy. Even the smaller species can put on quite a floral show. Rarely have I ever detected a scent from a Begonia bloom, nor have I ever detected nectar (though that's not to say either of those qualities don't exist). The point I am trying to make is that I couldn't quite figure out their strategy.

Sure, male flowers contain copious amounts of pollen. That is incentive enough to visit a male bloom. But what about the female flowers? Do they get away with not offering any sort of reward by simply being showy? Certainly that helps, however, female Begonia flowers sweeten the ruse with a bit of mimicry.

That is where the term pseudoanthery applies. Take a close look at the stigma of a begonia flower and you will be marveled by its intricate structure and bright coloration. As it turns out, the stigma is shaped in such a way as to mimic the pollen covered anthers of male flowers. Insects looking for protein rich pollen with visit the female flowers, realize it was all for naught, and move on. That is all the female flowers require. While the insect was busy searching for pollen, it is very likely that the bristly hairs on the stigma were able to pick up pollen grains from the insect's previous visit. With a little luck, that flower was a male begonia.

This ruse works best at large numbers. By producing lots of male flowers and considerably fewer female flowers, Begonias can ensure that the insects are not deterred by the lack of rewards. This has a double benefit for the plant as female flowers and seeds can be costly to produce.

Quite fascinating if I do say so myself. I have looked at countless Begonia flowers and not once did I question their structure. Just goes to show you that even old friends can teach us new things.

Further Reading: [1] [2]

A Peculiar Case of Bird Pollination

When we think of bird pollination, we often conjure images of a hummingbird sipping nectar from a long, tubular, red flower. Certainly the selection pressures brought about from entering into a pollination syndrome with birds has led to convergence in floral morphology across a wide array of different plant genera. Still, just when we think we have the natural world figured out, something new is discovered that adds more complexity into the mix. Nowhere is this more apparent than the peculiar relationship between an orchid and a bird native to South Africa.

The orchid in question is known scientifically as Disa chrysostachya. It is a bit of a black sheep of the genus. Whereas most Disa orchids produce a few large, showy flowers, this species produces a spike that is densely packed with minute flowers. They range from orange to red and, like most other bird pollinated flowers, produce no scent. 

Take the time to observe them in the field and you may notice that the malachite sunbird is a frequent visitor. The sunbirds perch themselves firmly on the spike and probe the shallow nectar spurs on each flower. At this point you may be thinking that the pollen sacs, or pollinia, of the orchid are affixed to the beak of the bird but, alas, you would be wrong. 

Closer inspection of the flowers reveal that the morphology and positioning of the pollinia are such that they simply cannot attach to the beak of the bird. The same goes for any potential insect visitors. The plant seems to have assured that only something quite specific can pick up the pollen. To see what is really going on, you would have to take a look at the sunbird's feet. 

That's right, feet. When a sunbird feeds at the flowers of D. chrysostachya, its feet position themselves onto the stiffened lower portion of the flower. This is the perfect spot to come into contact with the sticky pollinia. As the bird feeds, they pick up the pollinia on their claws! The next time the bird lands to feed, it will inevitably deposit that pollen. The orchids seemed to have benefited from the fact that once perched, sunbirds don't often reposition themselves on the flower spike. In this way, self pollination is minimized. A close relative, D. satyriopsis, has also appeared to enter into a pollination with sunbirds in a similar way. 

Though it may seem inefficient, research has shown that this pollination mechanism is quite successful for the orchid.The pollinia themselves stick quite strongly so that no amount of scuffing on branches or preening with beaks can dislodge them. Once pollination has been achieved, each flower is capable of producing thousands upon thousands of seeds.

Photo Credit: Johnson and Brown

Further Reading: [1]

A Shrub and Its Buffer Zone

Confession: I can be really bad at recognizing patterns. It's not my strong point. As such, I tend to remain skeptical of what I think I am seeing. Sometimes I am right, though. A recent stroke of luck came while I was hiking through some scrubby habitat in northern Florida. I walked out into a clearing to get a better view of a pond when I saw some interesting shrubs up on the banks. The area was largely covered in tufts of warm season grasses but the shrubs seemed to be ringed by barren, white sand. My botanist friend was kind enough to point out that the shrubs I was looking at were none other than sandhill rosemary (Ceratiola ericoides). With a name attached to these species, I could dive into the literature on this plant to see if I was actually seeing a true pattern or not.

Before we get to the meat of the article, it would be nice to first introduce you to the sandhill rosemary. C. ericoides is not a true rosemary at all. Its resemblance to the culinary mint is purely superficial. C. ericoides is a heath (family Ericaceae) and is the only member of its genus. It can be found growing in dry, scrubby habitats throughout southeastern North America. It is dioecious meaning each shrub is either male or female. Unlike its showier cousins, this heath is not pollinated by insects. Instead, it relies on wind. Because of this, C. ericoides flowers are highly reduced structures produced in the axils of leaves near the tips of its branches.

The scrubby habitats it calls home are challenging places for plants to live. The sandy soils drain water rapidly and are prone to shifting with the winds. The stout, needle like leaves are a fantastic adaptation for minimizing water loss during the hottest, driest months of the year. Also, regular fires are the norm. Burning is vital to the health of this region, however, C. ericoides does not seem to be very well adapted to cope with it. Instead, these shrubs are killed by fire, relying on the seed bank for regeneration. But that isn't the only thing this species has evolved in order to cope with a regular fire regime. As it turns out, C. ericoides may be utilizing chemical warfare to increase its chances of survival.

C. ericoides is what we call "allelopathic." Allelopathy can be defined as "the direct or indirect harmful or stimulatory effect of one plant on another through the production and release of chemical compounds" and is "an important form of plant-to-plant interference in natural and agricultural settings" (Rice 1984). In other words, allelopathic plants utilize chemicals that are toxic to other plants in order to gain an upper hand when it comes to acquiring space to grow. For C. ericoides, this may also mean keeping itself safe from fire.

As anyone who has tried to light a fire knows, a little fuel goes a long way. In the wild, plant materials make up the fuel load. The more plant material lying around, the more fuel the fire has to burn through. Much of the understory of these habitats are filled with fire adapted plant species. Grasses are possibly the most fire tolerant of them all. What's more, grasses often release specialized compounds when they burn that actually increase the temperature of the fire. This is often bad news for less fire adapted plants in the vicinity. If grasses and other fire adapted species were to be growing near C. ericoides, they would not only increase the chances of fire reaching the shrub but also increase the intensity of the flames. This is where the allelopathy comes in.

Evidence from greenhouse experiments has shown that the allelopathic compounds from C. ericoides inhibit the germination and growth of other plant species. This is especially true for fire adapted grasses. Although these chemicals are abundant in the leaves of C. ericoides, research also shows that they are produced in the roots as well. As the leaves fall off, they decompose and release their chemical cocktails into the soil immediately surrounding the shrub. This keeps plants at bay in the immediate vicinity while the roots go a bit further. Since the roots of C. ericoides branch outwards from the plant, the effectiveness of its chemical warfare is increased by a few meters radius around the shrub. Indeed, it is believed that C. ericoides is actually keeping the surrounding area clear of most fire adapted vegetation. In doing so, the shrubs are creating a fire-free buffer zone.

Although more work needs to be done in order to understand the degree to which these effects occur in the wild, this is nonetheless tantalizing evidence that such plant interactions are shaping the landscape in ways we don't fully understand. On a personal note, it was exciting to know that there really was something to the barren ring patterns I observed around each shrub.

Further Reading: [1] [2] [3]
 

Floral Deterrent

There is no mistaking the allure of certain floral scents. Entire industries have developed around capturing the essence of plant reproduction. Millions of years before we humans adopted floral scents for our own bidding, plants were producing them to attract pollinators. Even plants that produce sickening smells meant to mimic rotting flesh are trying to get the attention of something. It seems so obvious that these perfumes evolved as attractants but there are some plant species whose floral scents do the opposite. 

When I first caught a whiff of the blooms of the fragrant olive (Osmanthus fragrans) it didn't take long to track down its source. In my opinion it is one of the most enticing fragrances I have ever encountered. Native throughout much of Asia, this evergreen shrub produces sprays of tiny, pale, 4 lobed blossoms. Its attractive form and heavenly scent have led to its popularity in horticultural circles the world over. Surely its intense fragrance also makes it quite popular with pollinators. The truth is actually quite surprising.

In its native range, few insects seem to show it any attention. Aside from some hover flies, the list of floral visitors is surprisingly quite depauperate. What is going on? Why would this shrub go through the trouble of producing such volatile compounds? Has its intended pollinator gone extinct? Though it can be difficult to answer such inquiries, research done in Japan suggests that these scents may actually function as a deterrent rather than a lure. 

Researchers looked at a common butterfly species known to pollinate other flowering species in the area. The results of their experiments were quite shocking to say the least. Even when food was withheld for a period of time, the butterflies never visited the flowers of the fragrant olive. Only when the team replaced the flowers with replicas infused with a neutral scent did the butterflies pay them any attention. 

The fact that hover flies do in fact visit the flowers suggests that the scent compounds serve a dual function - attracting the intended pollinators while at the same time deterring potential nectar thieves. More work is needed before we can be completely confident in these conclusions but the idea nonetheless highlights the fact that more is going on with flowers than we realize. 

Photo Credit: hto2008 (http://bit.ly/2hPOhnO

Further Reading: [1]

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]

A Primer on Trigger Plants

I would like to introduce you to another group of plants capable of abrupt movements. Whereas many species have evolved moving parts in order to capture prey or deter herbivores, the following genus moves as means of achieving pollination. Meet the genus Stylidium a.k.a. the trigger plants.

Native to parts of Asia and Australia, these beautiful little herbs are quite diverse, making generalizations difficult. Still, there is one thing they all share, a fused set of reproductive organs that lash out at unsuspecting pollinators. When a visiting insects of sufficient size lands on a flower, its weight causes a rapid change in turgor pressure within the column's tissues.

The rapid change in pressure sends the column flying. The position of this reproductive hammer varies from species to species. Some bash their pollinators on the back whereas others strike them under the abdomen. When the flowers first mature, only the male portions are mature. Thus, the initial visit dusts the insect with pollen. Once the pollen is gone, the column resets itself and the female portions start to mature. The next time an insect visits the bloom, the stigma will do the bashing. With any luck, the visiting insect will have already been dusted with pollen from a previous plant. In this way, the plant avoids self pollination.

Another morphological aspect shared among member of this genus is the production of glandular trichomes. These minute hairs cover the body of the plant and produce sticky mucilage that ensnares tiny insects. It was originally thought that this was a merely a defense mechanism that may represent a form of proto-carnivory.

However, analysis of the mucilage revealed that plant is also producing digestive enzymes capable of breaking down insects unfortunate enough to have been caught. It remains to see whether or not the plants absorb nutrients in the same way as sundews but the fact that these plants share the same nutrient-poor habitats as many other Australian carnivores lends some credibility.

Photo Credit: http://bit.ly/2hJjMyc and Francis Nge

Further Reading: [1] [2]

The Ant-Farming Tillandsias

Tillandsias are all the rage. Their relative ease of care has found them included in seemingly every terrarium sold these days; often in very inappropriate circumstances that result in their death. There is no denying that these epiphytic relatives of the pineapple are unique and beautiful plants but I would argue that their ecology is probably the coolest aspect about them. I am particularly fond of the bulbous species because of their relationship with ants.

That's right, there are upwards of 13 species of bulbous Tillandsia that offer up housing for ants. If you look closely at the leaves of these species, you will notice that they roll up to form tubes that lead down into the bulb at the base. The space between the leaves forms a hollow chamber, functioning as a perfect microclimate for ants to nest. In many habitats, these Tillandsia offer better housing than the surrounding environment. One would be surprised at how many ants can fit in there too. Colonies containing anywhere between 100 - 300 ants are not unheard of.

The rewards for the plant are obvious. Ants provide nutrients as well as protection. In return the ants get a relatively safe and dry place to live. Ant domatia have been recorded in roughly 13 different species, many of which are some of the most commonly sold Tillandsias on the market such as T. baileyi, T. balbisiana, T. bulbosa, and T. caput-medusae. If this doesn't make your hanging glass Tillandsia orb even cooler then I don't know what will.

Photo Credits: scott.zona (http://bit.ly/16kZ1RR) and Alex Popovkin (http://bit.ly/1BXMEUH)

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. 

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

One of Ascension Island's endemic ferns - Pteris adscensionis

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.

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. 

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.

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)

The Ascension Island parsley fern (Anogramma ascensionis)

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)

The endemic Ascension spurge (Euphorbia origanoides)

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

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

 

A Cave Dwelling Nettle From China

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]

A Poop-Eating Pitcher Plant

The aerial pitchers of Nepenthes hemsleyana (http://bit.ly/2hC94fO) are quite unique in that they are not intended to catch insects. Instead, they have evolved as specialized roosts for Hardwicke's woolly bats (Kerivoula hardwickii). This incredible mutualism is quite unique among these tropical carnivores. The bats get a safe place to roost and in return, they deposit nitrogen-rich feces. 

This mutualism is quite remarkable in that the upper pitchers of N. hemsleyana have pretty much forgone insect capture altogether. Despite the obvious benefits of this evolutionary relationship, no one had bothered to quantify the benefits gained by turning insect catching pitchers into bat roosts. That is, until now. 

A team of researchers based out of University of Greifswald in Germany utilized some cunning methods to demonstrate exactly how much N. hemsleyana relies on bat droppings. What they found what quite remarkable. Plants offered only insects not only had fewer leaves, they also exhibited slower growth, reduced photosynthetic capacity, and reduced survival. It would seem that this mutualism has evolved to the point of being obligate. 

It is estimated that around 95% of the nitrogen needs of this plant are met by bat feces alone. As it turns out, nitrogen bound up in insect tissues were mostly unavailable to the plant. This is not the case for nitrogen in bat poop. Nitrogen deposited by bats comes mostly in the form of urea, which degrades into ammonium and is readily absorbed by the pitchers. 

Essentially Nepenthes hemsleyana now relies on bats to capture prey for them. This "ecological outsourcing," as it has been termed, frees the plant from the rigors of having to capture and digest insects on its own, thus saving valuable energy reserves that can be allocated to structures such as leaves, stems, and flowers. Why this species has evolved this strategy is anyone's guess. Perhaps it has to do with the deep shaded forest understory in which it grows. 

Photo Credit: Merlin Tuttle (www.merlintuttle.smugmug.com)

Further Reading: [1]

Ancient Green Blobs

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

In reality, this large mound is comprised of a colony of plants in the carrot family! Known scientifically as Azorella compacta, this species hails from the Andes and only grows between 3,200 and 4,500 metres in elevation. Its tightly compacted growth-form is an adaptation to this lifestyle, serving to prevent heat loss in such a cold and windy environment. Every so often, these mats erupt with tiny flowers, which must be a sight to behold!

The colonies expand at the rate of roughly 1.5 cm each year. Large colonies are estimated at over 3000 years old, making them some of the oldest living organisms on the planet! Sadly, the dense growth of the plant makes it highly sought after as a fuel source. Locals harvest the plant with pick axes and burn the dense mats for heat, not unlike peat from bogs. 

Because of its slow growth rate, harvesting this species has caused a serious decline in numbers. Local governments have since enacted laws to protect this species and some recovery has been documented though, with such slow growth rates, only time will tell if protection is enough. 

Photo Credits: [1] [2] 

Further Reading: [1]

High Elevation Record Breakers Are Evidence of Climate Change

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]

Shape Changing Flowers Attract Bats

For nectar feeding bats, finding food in a dense tropical rainforest is a complex task. For many years it was thought that nectar feeding bats relied solely on scent to find their food. Unlike insects that move around, flowers are stationary. That all changed once we developed microphones sensitive enough to pick up bat calls.

It turns out, nectar feeding bats utilize different frequencies for echolocation that are primed for resolving finer details than those of their insect feeding cousins. Obviously this works quite well for the bats as they are very important pollinators. Whereas many bat pollinated plants position their flowers in easy to reach places for bats, others take it a step further.

Some plant species couple their floral displays with specialized structures that are prime reflectors for bat sonar. Recently, a species of vine known scientifically as Marcgravia evenia (http://bit.ly/2h358BF) was made famous the world over for the satellite dish shaped leaves it produces just above its inflorescence. However, this species is not alone. Other plants have managed to tap into bat sonar in some very interesting ways. Take, for instance, the bizarrely beautiful blooms of the sea bean.

A member of the legume family, Mucuna holtonii is neotropical in its distribution. It is a vining species that snakes its way up into the canopy. When in flower, the plant produces a stunning pendulum-shaped inflorescence, the end of which is ringed in flowers. Although highly derived for this group, the flowers are nonetheless representative of the family. Their secret to success lies in the single large petal known as the banner or vexillum coupled with some explosive power.

This banner petal acts as a nectar guide, though not in a strictly visual sense. These flowers open at night when nectar feeding bats are out and about. They emit a scent, which likely lets the bats know roughly when and where a meal is available. Unlike bees, however, these bats have no interest in pollen. Instead, they are after the energy-rich nectar reserves that only virgin flowers produce. And they produce quite a bit (relative to their size), upwards of 100 microliters.

Bats that have honed in on the scent are further attracted to the flowers by the shape of the vexillum. Supremely adapted to the specific frequency of these nectar feeding bats, the vexillum of each virgin flower reflects sound waves over a greater range of directions than the clutter of the surrounding forest, thus helping the bats zero in on exactly where they need to be.

Unlike many other bat pollinated flowers, those of M. holtonii cannot be accessed simply by hovering. A bat must land on them in order to access the nectar within. The weight of the bat is what the flowers require to complete the process. When a visiting bat lands on the flower, it triggers an explosive mechanism that snaps the anthers outward, causing pollen to explode from the flower, spattering it all over the bat's back.

Once the bat drinks its fill, nectar production ceases. However, the flowers don't senesce at this point. They still provide a calling card for any other flowers yet to be visited. Despite the fact that they stick around, it has been found that bats are significantly less likely to visit spent flowers. How do they know?

The answer again lies in that banner petal. Once the flowers have been triggered, its shape changes. This results in a change in the way in which bats perceive the flowers via echolocation. Bats soon learn that flowers with this altered shape no longer offer a nectar reward. The plant benefits from this because it reduces the chance that a bat will end up depositing its pollen right back on the flower it came from. It's win win when you think about it. Bats maximize their meals and the plant maximizes its chances of cross pollination.

Photo Credit: Merlin Tuttle

Further Reading: [1] [2] 

Catnip and Cats

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

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 quite active. 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. 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 this 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 sound of an insect chewing on leaves. This causes an uptick in the production of defense compounds. Perhaps the telegraph plant, when sensing sound waves, increases its movements in order 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.

Photo Credit: [1]

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

Wasabi

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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

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

The aptly named 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 has 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.

These 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 pitchers 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 save 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 recent 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.

The microbes release certain 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's surface 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 very likely makes a big difference for these carnivores living in such nutrient poor conditions.

Photo Credit: Wikimedia Commons

Further Reading: [1]