The Ancient Green Blobs of the Andes

Photo by Atlas of Wonders licensed under CC BY-NC-ND 2.0

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!

These large, green mounds are comprised of a colony of plants in the carrot family! The Yareta, or Azorella compacta, hails from the Andes and only grows between 3,200 and 4,500 meters (10,500 - 14,750 ft) in elevation. Its tightly compacted growth habit is an adaptation to its high elevation lifestyle. Cushion growth like this helps these plants prevent heat and water loss in these cold, dry, windy environments.

Every so often, these mats erupt with tiny flowers, which must be a sight to behold! Photo by Lon&Queta licensed under CC BY-NC-SA 2.0

As you might imagine, these plants are extremely slow growers. By studying their growth rates over time, experts estimate that individual colonies expand at the rate of roughly 1.5 cm each year. By extrapolating these rates to the measurements of large colonies, we get a remarkable picture of how old some of these plants truly are. Indeed, some of the largest 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. Massive chunks of these plants are harvested with pick axes and burned as a source of heat. Due to their slow growth rate, overharvesting in recent years has caused a serious decline in Yareta populations. Local governments have since enacted laws to protect this species in hopes that it will give colonies the time they need to recover. Indeed, some recovery has already been documented, however, continued monitoring and management will be needed to ensure their populations remain viable into the foreseeable future.

Photo Credits: [1] [2]

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

How Overharvesting is Changing an Alpine Plant in China

[Source]

We are increasingly becoming aware of the importance of camouflage in the plant kingdom. By blending in with their surroundings, some plants are able to avoid attention from hungry herbivores. Amazingly, a recent investigation in Hengduan Mountains of southwest China has revealed that it can also help plants avoid being harvested for the herbal trade.

Fritillaria delavayi is a tiny, alpine plant that grows among the rocky scree at high elevations in the Hengduan Mountains. It is a slow growing plant that can take upwards of 5 years to produce its first flower. It is also variable in its overall coloration. Some populations consist of plants with green leaves and bright yellow flowers, whereas other populations consist of plants with leaves and flowers in various shades of brown that cause them to blend in with the surrounding rock.

Variation in plant coloration is not terribly novel. Many plant populations can differ from one another in their overall appearance, however, there seems to be a pattern among F. delavayi. It would seem that plants growing in more accessible places tend to be brown whereas plants growing in less accessible places tend to be green and yellow. Interestingly, herbivores don’t seem to explain these differences. Indeed, F. delavayi is chock full of toxic alkaloids that deter what few herbivores exist at such high elevations. Nonetheless, it is the presence of those alkaloids that explain why populations differ so much from one area to the next.

View fullsize

(A and B) Normal green individuals in populations with low harvest pressure. (C and D) Camouflaged individuals in populations with high harvest pressure [SOURCE]

Because of their purported medicinal value, the demand for F. delavayi bulbs has greatly increased over time. Each year more and more people are heading to these mountains to harvest the plants to sell them in herbal markets. This led a team of researchers to investigate if harvesting by humans could explain color variations among populations.

Amazingly, it did! By looking at ease of access and harvesting, researchers found that plants that were in hard to reach areas or places where harvesting is difficult were more likely to have bright green leaves and yellow flowers. By contrast, plants in easy to reach locations that were not difficult to harvest were more likely to be brown. The researchers even went the extra mile and tested how easily plants of each coloration could be found by humans. Not surprisingly, it took humans much longer to find brown plants that it did for them to find green plants.

Based on their findings, researchers have concluded that harvesting pressures are changing F. delavayi populations in the Hengduan Mountains. Because they are harder to detect and therefore less likely to be harvested, plants sporting the brown coloration are far more likely to survive and reproduce in highly trafficked areas, resulting in an increase in camouflaged offspring. Alternatively, populations growing in hard to reach areas do not experience such heavy selection pressures and can continue to safely sport bright green leaves and yellow flowers. It just goes to show you that human activities can often have unintended consequences for other species. This research also raises the question of how humans have shaped the defensive strategies of other highly sought after plant species.

Photo Credits: [1] [2]

Further Reading: [1]

Himalayan snowball plants and their fashionably functional coats

Credit to CGTN Nature film crew

Hairy plants are both fun and functional. Hairs or trichomes on the leaves of plants can serve a variety of functions. If the plant is growing in a region prone to cold temperatures, it is thought that a dense layer of hairs can function like a wool coat, keeping the plant warm when temperatures drop. This is such a popular idea that it is often assumed rather than tested. For a strange group commonly referred to as Himalayan snowball plants, the truth is a bit more complicated.

Himalayan snowball plants are members of the genus Saussurea, which hails from the family Asteraceae. Though the genus is widespread, the Himalayan snowball plants are confined to high elevation, alpine habitats in central Asia. As you can imagine, life at such altitudes is defined by extremes. Temperatures during the day can skyrocket due to the lack of atmospheric insulation. Conversely, temperatures can take a dive as weather changes and/or the sun goes down. One look at the Himalayan snowball plants tells you that these plants are wonderfully adapted to such habitats. But what kind of advantages does that this coat of hair provide?

Credit to CGTN Nature film crew

Well, research has revealed a bit more nuance to the whole “winter coat” idea. Indeed, it does appear that the furry coat does in fact provide some insulation to the plant. However, most of the warmth appears to come from the dark color of the inflorescence rather than by pure insulation alone. After all, the vast majority of plants do not produce any heat. The flower heads or capitula of these daisy relatives is low in stature. This keeps it out of the way of the coldest winds. Also, they are so deeply violet in color that they can appear black. This is no accident. As anyone can tell you, darker colors absorb more heat and that is exactly what happens with the Himalayan snowball plants.

Another interesting thing to consider is that most of the growth and reproduction in these plants occurs during frost-free periods of the year. Though temperature swings are frequent, it rarely gets cold enough to severely damage plant tissues until long after the plants have flowered and set seed. Moreover, there is some evidence to suggest that the dense coat of hairs may have a cooling effect during periods of intense exposure to sunlight. Their light color may reflect a lot of the incoming radiation, sparing the plant from overheating. Therefore, it appears that the benefit of such a thick coat of hairs has more to do with avoiding temperature swings than it does ensuring constant warmth. By buffering the plant against huge swings in ambient temperature, the hairs are able to maintain more favorable conditions for plant growth and reproduction.

Credit to CGTN Nature film crew

Also, because this area experiences a monsoon season during growth and flowering of Himalayan snowball plants, these hairs may also serve to repel water, keeping the plants from becoming completely saturated. If water were to stick around for too long, it could open the plant up to pathogens like fungi and bacteria. It could also be that by insulating the plant against temperature swings, the hairs also provide a more favorable microclimate for pollinators. Bumblebees are thought to be the main pollinators of Himalayan snowball plants and despite their ability to maintain higher internal temperatures relative to their surroundings, anything that can buffer them as they feed would be beneficial to both the bees and whatever plant they may be pollinating as a result.

Photo Credit: [1]

Further Reading: [1] [2]

A New Case of Lizard Pollination from South Africa

With its compact growth habit and small, inconspicuous flowers tucked under its leaves, it seems like Guthriea capensis doesn’t want to be noticed. Indeed, it has earned itself the common name of '“hidden flower.” That’s not to say this plant is unsuccessful. In fact, it seems to do just fine tucked in among high-elevation rock crevices of its home range along the Drakensberg escarpment of South Africa. Despite its cryptic nature, something must be pollinating these plants and recent research has finally figured that out. It appears that the hidden flower has a friend in some local reptiles.

Lizard pollination is not unheard of ([1] & [2]), however, it is by no means a common pollination syndrome. This could have something to do with the fact that we haven’t been looking. Pollination studies are notoriously tricky. Just because something visits a flower does not mean its an effective pollinator. To investigate this properly, one needs ample hours of close observation and some manipulative experiments to get to the bottom of it. Before we get to that, however, its worth getting to know this strange plant in a little more detail.

The hidden flower is a member of an obscure family called Achariaceae. Though a few members have managed to catch our attention economically, most genera are poorly studied. The hidden flower itself appears to be adapted to high elevation environments, hence its compact growth form. By hugging the substrate, this little herb is able to avoid the punishing winds that characterize montane habitats. Plants are dioecious meaning individuals produce either male or female flowers, never both. The most interesting aspect of its flowers, however, are how inconspicuous they are.

The hidden flower (Guthriea capensis) in situ.

Flowers are produced at the base of the plant, out of site from most organisms. They are small and mostly green in color except for the presence of a few bright orange glands near the base of the style, deep within the floral tube. What they lack in visibility, they make up for in nectar and smell. Each flower produced copious amounts of sticky, sugar-rich nectar. They are also scented. Taken together, these traits usually signal a pollination syndrome with tiny rodents but this assumption appears to be wrong.

Based on hours of video footage and a handful of clever experiments, a team of researchers from the University of KwaZulu-Natal and the University of the Free State have been able to demonstrate that lizards, not mammals, birds, or insects are the main pollinators of this cryptic plant. Two species of lizard native to this region, Pseudocordylus melanotus and Tropidosaura gularis, were the main floral visitors over the duration of the study period.

Pseudocordylus melanotus

Tropidosaura gularis photo © 2009 Serban Proches licensed under CC BY-SA 2.5

Visiting lizards would spend time lapping up nectar from several flowers before moving off and in doing so, picked up lots of pollen in the process. Being covered in scales means that pollen can have a difficult time sticking to the face of a reptile but the researchers believe that this is where the sticky pollen comes into play. It is clear that the pollen adheres to the lizards’ face thanks to the fact that they are usually covered in sticky nectar. By examining repeated feeding attempts on different flowers, they also observed that not only do the lizards pick up plenty of pollen, they deposit it in just the right spot on the stigma for pollination to be successful. Insect visitors, on the other hand, were not as effective at proper pollen transfer.

Conspicuously absent from the visitation roster were rodents. The reason for this could lie in some of the compounds produced within the nectar. The team found high levels of a chemical called safranal, which is responsible for the smell of the flowers. Safranal is also bitter to the taste and it could very well serve as a deterrent to rodents and shrews. More work will be needed to confirm this hypothesis. Whatever the case, safranal does not seem to deter lizards and may even be the initial cue that lures them to the plant in the first place. Tongue flicking was observed in visiting lizards, which is often associated with finding food in other reptiles.

Male flower (a) and female flower (b). Note the presence of the orange glands at the base.

Another interesting observation is that the color of the floral tube and the orange glands within appear to match the colors of one of the lizard pollinators (Pseudocordylus subviridis ). Is it possible that this is further entices the lizards to visit the flowers? Other reptile pollination systems have demonstrated that lizards appear to respond well to color patterns for which they already have some sort of sensory bias. Is it possible that these flowers evolved in response to such a bias? Again, more work will be needed to say for sure.

By excluding vertebrates from visiting the flowers, the team was able to show that indeed lizards appear to be the main pollinators of these plants. Without pollen transfer, seed set is reduced by 95% wheres the additional exclusion of insects only reduced reproductive success by a further 4%. Taken together, it is clear that lizards are the main pollinators of the enigmatic hidden flower. This discovery expands on our limited knowledge of lizard pollination syndromes and rises many interesting questions about how such relationships evolve.

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

Further Reading: [1] [2]

The Creeping Strawberry Pine

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

With its small, creeping habit and bright red, fleshy female cones, it is easy to see how Microcachrys tetragona earned its common name “creeping strawberry pine.” This miniature conifer is as adorable as it is interesting. With a fossil history that spans 66 million years of Earth’s history, it also has a lot to teach us about biogeography.

Today, the creeping strawberry pine can only be found growing naturally in western Tasmania. It is an alpine species, growing best in what is commonly referred to as alpine dwarf scrubland, above 1000 m (3280 ft) in elevation. Like the rest of the plants in such habitats, the creeping strawberry pine does not grow very tall at all. Instead, it creeps along the ground with its prostrate branches that barely extend more than 30 cm (0.9 ft) above the soil. This, of course, is likely an adaptation to its alpine environment. Plants that grow too tall frequently get knocked back by brutal winds and freezing temperatures among other things.

The creeping strawberry pine is not a member of the pine family (Pinaceae) but rather the podocarp family (Podocarpaceae). This family is interesting for a lot of reasons but one of the coolest is the fact that they are charismatic representatives of the so-called Antarctic flora. Along with a handful of other plant lineages, it is thought that Podocarpaceae arose during a time when most of the southern continents were combined into a supercontinent called Gondwana. Subsequent tectonic drift has seen the surviving members of this flora largely divided among the continents of the Southern Hemisphere. By combining current day distributions with fossil evidence, researchers are able to use families such as Podocarpaceae to tell a clearer picture of the history of life on Earth.

What is remarkable is that among the various podocarps, the genus Microcachrys produces pollen with a unique morphology. When researchers look at pollen under the microscope, whether extant or fossilized, they can say with certainty if it belongs to a Microcachrys or not. The picture we get from fossil evidence paints an interesting story for Microcachrys diversity compared to what we see today. It turns out, Microcachrys endemic status is a more recent occurrence.

This distinctive, small, trisaccate pollen grain is typical of what you find with Microcachrys whereas all other podocarps produce bisaccate pollen. J.I. Raine, D.C. Mildenhall, E.M. Kennedy (2011). New Zealand fossil spores and pollen: an illustrated catalogue. 4th edition. GNS Science miscellaneous series no. 4. http://data.gns.cri.nz/sporepollen/index.htm

The creeping strawberry pine is what we call a paleoendemic, meaning it belongs to a lineage that was once far more widespread but today exists in a relatively small geographic location. Fossilized pollen from Microcachrys has been found across the Southern Hemisphere, from South America, India, southern Africa, and even Antarctica. It would appear that as the continents continued to separate and environmental conditions changed, the mountains of Tasmania offered a final refuge for the sole remaining species in this lineage.

Another reason this tiny conifer is so charming are its fruit-like female cones. As they mature, the scales around the cone swell and become fleshy. Over time, they start to resemble a strawberry more than anything a gymnosperm would produce. This is yet another case of convergent evolution on a seed dispersal mechanism among a gymnosperm lineage. Birds are thought to be the main seed dispersers of the creeping strawberry pine and those bright red cones certainly have what it takes to catch the eye of a hungry bird. It must be working well for it too. Despite how narrow its range is from a global perspective, the creeping strawberry pine is said to be locally abundant and does not face the same conservation issues that many other members of its family currently face. Also, its unique appearance has made it something of a horticultural curiosity, especially among those who like to dabble in rock gardening.

Mature female cones look more like angiosperm fruit than a conifer cone. Photo by Mnyberg licensed under CC BY-SA 4.0

Photo Credits: [1] [2] [3] [4]

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

Meet Jones' Columbine

Photo by Steve licensed under CC BY-NC-SA 2.0

Meet Aquilegia jonesii. This interesting little columbine can be found growing in a narrow range along the northern Rockies. It only grows in alpine and sub-alpine zones, making it quite rare. It has a cushion-like growth form to shield it from the elements but disproportionately large flowers. It is a lucky day if one stumbles across this species! 

Fun Fact: Both the common name and generic name of the flowers referred to collectively as "columbines" have their origins in ornithology? 

That's right, the genus to which they belong, Aquilegia, can trace its origin to the word "aquila," which is Latin for "eagle." When the genus was being described, it was felt that the flower resembled the claw of an eagle. 

The word "columbine" has it's origins in the word "columba," which is Latin for "pigeon" or "dove." Early botanical enthusiasts felt that the nectar spurs resembled the heads of a group of doves. 

More and more I am coming on board with the idea that etymology can be quite fun.

Photo Credit: Steve (http://bit.ly/NbGbmz)

Further Reading: [1] [2] [3]

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]

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]

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]