On the Flora of Antarctica

Antarctica – the frozen continent. It is hard to think of a place on Earth that is less hospitable to life. Yet life does exist here and some of it is botanical. Though few in number, Anarctica’s diminutive flora is able to eke out an existence wherever the right conditions present themselves. It goes without saying that these plants are some of the hardiest around.

It is strange to think of Antarctica as having any flora at all. How many descriptions of plant families and genera say something to the effect of “found on nearly every continent except for Antarctica.” It didn’t always used to be this way though. Antarctica was once home to a diverse floral assemblage that rivaled anything we see in the tropics today. Millions upon millions of years of continental drift has seen this once lush landmass positioned squarely at Earth’s southern pole.

Situated that far south, Antarctica has long since become a frozen wasteland of sorts. The landscape is essentially a desert. Instead of no precipitation, however, most water in this neck of the woods is completely locked up in ice for most of the year. This is one reason why plants have had such a hard time making a living here. That is not to say that some plants haven’t made it. In fact, a handful of species thrive under these conditions.

When anyone goes looking for plants in Antarctica, they must do so wherever conditions ease up enough for part of the year to allow terrestrial life to exist. In the case of this frozen continent, this means hanging out along the coast or one of handful of islands situated just off of the mainland. Here, enough land thaws during the brief summer months to allow a few plant species to take root and grow.

The flora of Antarctica proper consists of 2 flowering plant species, about 100 species of mosses, and roughly 30 species of liverwort. The largest of these are the flowering plants – a grass known as Antarctic hair grass (Deschamsia antarctica), and member of the pink family with a cushion-like growth habit called Antarctic pearlwort (Colobanthus quitensis). Whereas the hair grass benefits from being wind pollinated, the Antarctic pearlwort has had to get creative with its reproductive needs. Instead of relying on pollinators, which simply aren’t present in any abundance on Antarctica, it appears that the pearlwort has shifted over to being entirely self-pollinated. This seems to work for it because if the mother plant is capable of living on Antarctica, so too will its clonal offspring.

By far the dominant plant life on the continent are the mosses. With 100 species known to live on Antarctica, it is hard to make generalizations about their habits other than to say they are pretty tough plants. Most live out their lives among the saturated rocks of the intertidal zones. What we can say about these mosses is that they support a bewildering array of microbial life, from fungi and lichens to protists and tardigrades. Even in this frozen corner of the world, plants form the foundation for all other forms of life.


The coastal plant communities of Antarctica represent hotbeds of biodiversity for this depauperate continent. They reach their highest densities on the Antarctic Peninsula as well as on coastal islands such as south Orkney Islands and the South Shetland Islands. Here, conditions are just mild enough among the various rocky crevices for germination and growth to occur. Still, life on Antarctica is no cake walk. A short growing season, punishing waves, blistering winds, and trampling by penguins and seals present quite a challenge to Antarctica’s botanical denizens. They are able to live here despite these challenges.

Still, humans take their toll. The Antarctic Peninsula is experiencing some of the most rapid warming on the planet over the last century. As this region grows warmer and drier each year, plants are responding accordingly. Antarctic mosses along the peninsula are increasingly showing signs of stress. They are starting to prioritize the production of protective pigments in their tissues over growth and reproduction. Moreover, new species of moss are starting to take over. Rapid warming and drying of the Antarctic Peninsula appears to be favoring species that are more desiccation tolerant at the expense of the continents endemic moss species.

Changes in the structure and composition of Antarctica’s moss beds is far from being a scientific curiosity for only bryologists to ponder. It is a symptom of greater changes to come.

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

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

Gymnosperms and Fleshy “Fruits”

Many of us were taught in school that one of the key distinguishing features between gymnosperms and angiosperms is the production of fruit. Fruit, by definition, is a structure formed from the ovary of a flowering plant. Gymnosperms, on the other hand, do not enclose their ovules in ovaries. Instead, their unfertilized ovules are exposed (to one degree or another) to the environment. The word “gymnosperm” reflects this as it is Greek for “naked seed.” However, as is the case with all things biological, there are exceptions to nearly every rule. There are gymnosperms on this planet that produce structures that function quite similar to fruits.

The key to understanding this evolutionary convergence lies in understanding the benefits of fruits in the first place. Fruits are all about packing seeds into structures that appeal to the palates of various types of animals who then eat said fruits. Once consumed, the animals digest the fruity bits and will often deposit the seeds elsewhere in their feces. Propagule dispersal is key to the success of plants as it allows them to not only to complete their reproductive cycle but also conquer new territory in the process. With a basic introduction out of the way, let’s get back to gymnosperms.

There are 4 major gymnosperm lineages on this planet – the Ginkgo, cycads, gnetophytes, and conifers. Each one of these groups contains members that produce fleshy structures around their seeds. However, their “fruits” do not all develop in the same way. The most remarkable thing to me is that, from a developmental standpoint, each lineage has evolved its own pathway for “fruit” production.

For instance, consider ginkgos and cycads. Both of these groups can trace their evolutionary history back to the early Permian, some 270 – 280 million years ago, long before flowering plants came onto the scene. Both surround their developing seed with a layer of protective tissue called the integument. As the seed develops, the integument swells and becomes quite fleshy. In the case of Ginkgo, the integument is rich in a compound called butyric acid, which give them their characteristic rotten butter smell. No one can say for sure who this nasty odor originally evolved to attract but it likely has something to do with seed dispersal. Modern day carnivores seem to be especially fond of Ginkgo “fruits,” which would suggest that some bygone carnivore may have been the main seed disperser for these trees.

The Gnetophytes are represented by three extant lineages (Gnetaceae, Welwitschiaceae, and Ephedraceae), but only two of them – Gnetaceae and Ephedraceae– produce fruit-like structures. As if the overall appearance of the various Gnetum species didn’t make you question your assumptions of what a gymnosperm should look like, its seeds certainly will. They are downright berry-like!

The formation of the fruit-like structure surrounding each seed can be traced back to tiny bracts at the base of the ovule. After fertilization, these bracts grow up and around the seed and swell to become red and fleshy. As you can imagine, Gnetum “fruits” are a real hit with animals. In the case of some Ephedra, the “fruit” is also derived from much larger bracts that surround the ovule. These bracts are more leaf-like at the start than those of their Gnetum cousins but their development and function is much the same.

Whereas we usually think of woody cones when we think of conifers, there are many species within this lineage that also have converged on fleshy structures surrounding their seeds. Probably the most famous and widely recognized example of this can be seen in the yews (Taxus spp.). Ovules are presented singly and each is subtended by a small stalk called a peduncle. Once fertilized, a group of cells on the peduncle begin to grow and differentiate. They gradually swell and engulf the seed, forming a bright red, fleshy structure called an “aril.” Arils are magnificent seed dispersal devices as birds absolutely relish them. The seed within is quite toxic so it usually escapes the process unharmed and with any luck is deposited far away from the parent plant.

Another great example of fleshy conifer “fruits” can be seen in the junipers (Juniperus spp.). Unlike the other gymnosperms mentioned here, the junipers do produce cones. However, unlike pine cones, the scales of juniper cones do not open to release the seeds inside. Instead, they swell shut and each scale becomes quite fleshy. Juniper cones aren’t red like we have seen in other lineages but they certainly garnish the attention of many a small animal looking for food.

I have only begun to scratch the surface of the fruit-like structures in gymnosperms. There is plenty of literary fodder out there for those of you who love to read about developmental biology and evolution. It is a fascinating world to uncover. More importantly, I think the fleshy “fruits” of the various gymnosperm lineages stand as a testament to the power of natural selection as a driving force for evolution on our planet. It is amazing that such distantly related plants have converged on similar seed dispersal mechanisms by so many different means.

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

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

How 2 New York Women Erased $1.5 Million In Me…

How 2 New York Women Erased $1.5 Million In Medical Debt For Hundreds Of Strangers:

Some New Yorkers received an early Christmas present this year – a little, yellow envelope that came through the mail, inside, a letter telling the person that their medical debt has been forgiven. This act of kindness comes courtesy of Carolyn Kenyon and Judith Jones, who both live in Ithaca, N.Y. The two friends met through the Finger Lakes chapter of the Campaign for New York Health.

They’re both big supporters of a single-payer health system. And they were looking for a project to work on together to highlight the problems with the health care system. They decided on medical debt.

The Hole Story: How Mosquitoes Seek Out Gaps i…

The Hole Story: How Mosquitoes Seek Out Gaps in Nets or Screens:

SCIENCE SUNDAY

Assassin fly babies have ‘Swiss army knife’ mo…

Assassin fly babies have ‘Swiss army knife’ mouths 

Australia’s splendid assassin fly (Blepharotes splendidissimus) earns its fearsome moniker. About the size of a bottle cap and sporting a similar metallic luster, they ambush butterflies and dragonflies in midair, killing them with a venomous bite. Now, scientists have discovered that even the larvae of these flies are vicious.

The mouths of these maggots are “the insect equivalent of a Swiss army knife,” researchers report in Austral Entomology. Using scanning electron microscopy to produce photos like the one above, the team discovered blade-shaped mandible hooks with backward-pointing teeth—all the better to pierce into soft-bodied bugs in the soil where these larvae live. These hooks also have grooves that, when pushed together, form a tube the maggots use to inject venomous saliva into their prey. The venom injector tool doubles as a straw, allowing the larvae to suck out the body parts of their victims, the authors report.

World’s First Insect Vaccine Could Help …

In all the years of concern about collapsing bee colonies around the world, I have never once heard about AFB – mentioned or implicated. Don’t think “bee problem solved!” We still need to deal with the pesticide issue.

World’s First Insect Vaccine Could Help Bees Fight Off Deadly Disease 

Bees may soon get an ally in their fight against bacterial disease — one of the most serious threats the pollinators face — in the form of an edible vaccine. That’s the promise held out by researchers in Finland, who say they’ve made the first-ever vaccine for insects, aimed at helping struggling honeybee populations.

The scientists are targeting one of bees’ most deadly enemies: American foulbrood, or AFB, an infectious disease that devastates hives and can spread at a calamitous rate. Often introduced by nurse bees, the disease works by bacteria feeding on larvae — and then generating more spores, to spread further.

The Plight of the African Violets

For many of us, African violets (Saintpaulia spp.) are some of the first houseplants we learned how to grow. They are not true violets (Violaceae), of course, but rather members of the family Gesneriaceae. Nonetheless, their compact rosettes of fuzzy leaves coupled with regular sprays of colorful flowers has made them a multi-million dollar staple of the horticultural industry. Unfortunately their numbers in captivity overshadow a bleak future for this genus in the wild. Many African violets are teetering on the brink of extinction.

The genus Saintpaulia is endemic to a small portion of east Africa, with a majority of species being found growing at various elevations throughout the Eastern Arc Mountains of Kenya and Tanzania. Most of the plants we grow at home are clones and hybrids of two species, S. ionantha and S. confusa. Collected in 1892, these two species were originally thought to be the same species, S. ionantha, until a prominent horticulturist noted that there are distinct differences in the seed capsules each produced. Since the 1890’s, more species have been discovered.

Exactly how many species comprise this genus is still up for some debate. Numbers range from as many as 20 to as few as 6. Much of the early work on describing various Saintpaulia species involved detailed descriptions of the density and direction of hairs on the leaves. More recent genetic work considers some of these early delineations to be tenuous at best, however, even these modern techniques have resolved surprisingly little when it comes to a species concept within this group.

Though it can be risky to try and make generalizations about an entire genus, there are some commonalities when it comes to the habitats these plants prefer. Saintpaulia grow at a variety of elevations but most can be found growing on rocky outcrops. Most of them prefer growing in the shaded forest understory, hence they do so well in our (often) poorly lit homes. Their affinity for growing on rocks means that many species are most at home growing on rocks and cliffs near streams and waterfalls. The distribution of most Saintpaulia species is quite limited, with most only known from a small region of forest or even a single mountain. Its their limited geographic distribution that is cause for concern.

Regardless of how many species there are, one fact is certain – many Saintpaulia risk extinction if nothing is done to save them. Again, populations of Saintpaulia species are often extremely isolated. Though more recent surveys have revealed that a handful of lowland species are more widespread than previously thought, mid to highland species are nonetheless quite restricted in their distribution. Habitat loss is the #1 threat facing Saintpaulia. Logging, both legal and illegal, and farming are causing the diverse tropical forests of eastern Africa to shrink more and more each year. As these forests disappear, so do Saintpaulia and all of the other organisms that call them home.

There is hope to be had though. The governments of Kenya and Tanzania have recognized that too much is being lost as their forests disappear. Stronger regulations on logging and farming have been put into place, however, enforcement continues to be an issue. Luckily for some Saintpaulia species, the type localities from which they were described are now located within protected areas. Protection coupled with inaccessibility may be exactly what some of these species need to survive. Also, thanks to the ease in which Saintpaulia are grown, ex situ conservation is proving to be a viable and valuable option for conserving at least some of the genetic legacy of this genus.

It is so ironic to me that these plants can be so common in our homes and offices and yet so rare in the wild. Despite their popularity, few recognize the plight of this genus. My hope is that, in reading this, many of you will think about what you can do to protect the legacy of plants like these and so many others. Our planet and the species that call it home are doomed without habitat in which to live and reproduce. This is why land conservation is an absolute must. Consider donating to a land conservation organization today. Here are two worth your consideration:

The Nature Conservancy

The Rainforest Trust

Photo Credits: [1][2][3][4][5]

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

The Rise and Fall of the Scale Trees

If I had a time machine, the first place I would visit would be the Carboniferous. Spanning from 358.9 to 298.9 million years ago, this was a strange time in Earth’s history. The continents were jumbled together into two great landmasses – Laurasia to the north and Gondwana to the south and the equatorial regions were dominated by humid, tropical swamps. To explore these swamps would be to explore one of the most alien landscapes this world has ever known.

The Carboniferous was the heyday for early land plants. Giant lycopods, ferns, and horsetails formed the backbone of terrestrial ecosystems. By far the most abundant plants during these times were a group of giant, tree-like lycopsids known as the scale trees. Scale trees collectively make up the extinct genus Lepidodendron and despite constantly being compared to modern day club mosses (Lycopodiopsida), experts believe they were more closely related to the quillworts (Isoetopsida).

It is hard to say for sure just how many species of scale tree there were. Early on, each fragmentary fossil was given its own unique taxonomic classification; a branch was considered to be one species while a root fragment was considered to be another and juvenile tree fossils were classified differently than adults. As more complete specimens were unearthed, a better picture of scale tree diversity started to emerge. Today I can find references to anywhere between 4 and 13 named species of scale tree and surely more await discovery. What we can say for sure is that scale tree biology was bizarre.

The name “scale tree” stems from the fossilized remains of their bark, which resembles reptile skin more than it does anything botanical. Fossilized trunk and stem casts are adorned with diamond shaped impressions arranged in rows of ascending spirals. These are not scales, of course, but rather they are leaf scars. In life, scale trees were adorned with long, needle-like leaves, each with a single vein for plumbing. Before the started branching, young trees would have resembled a bushy, green bottle brush.

As scale trees grew, it is likely that they shed their lower leaves, which left behind the characteristic diamond patterns that make their fossils so recognizable. How these plants achieved growth is rather fascinating. Scale tree cambium was unifacial, meaning it only produced cells towards its interior, not in both directions as we see in modern trees. As such, only secondary xylem was produced. Overall, scale trees would not have been very woody plants. Most of the interior of the trunk and stems was comprised of a spongy cortical meristem. Because of this, the structural integrity of the plant relied on the thick outer “bark.” Many paleobotanists believe that this anatomical quirk made scale trees vulnerable to high winds.

Scale trees were anchored into their peaty substrate by rather peculiar roots. Originally described as a separate species, the roots of these trees still retain their species name. Paleobotanists refer to them as “stigmaria” and they were unlike most roots we encounter today. Stigmaria were large, limb-like structures that branched dichotomously in the soil. Each main branch was covered in tiny spots that were also arranged in rows of ascending spirals. At each spot, a rootlet would have grown outward, likely partnering with mycorrhizal fungi in search of water and nutrients.

Eventually scale trees would reach a height in which branching began. Their tree-like canopy was also the result of dichotomous branching of each new stem. Amazingly, the scale tree canopy reached staggering heights. Some specimens have been found that were an estimated 100 ft (30 m) tall! It was once thought that scale trees reached these lofty heights in as little as 10 to 15 years, which is absolutely bonkers to think about. However, more recent estimates have cast doubt on these numbers. The authors of one paper suggest that there is no biological mechanism available that could explain such rapid growth rates, concluding that the life span of a typical scale tree was more likely measured in centuries rather than years.

Regardless of how long it took them to reach such heights, they nonetheless would have been impressive sites. Remarkably, enough of these trees have been preserved in situ that we can actually get a sense for how these swampy habitats would have been structured. Whenever preserved stumps have been found, paleobotanists remark on the density of their stems. Scale trees did not seem to suffer much from overcrowding.

The fact that they spent most of their life as a single, unbranched stem may have allowed for more success in such dense situations. In fact, those that have been lucky enough to explore these fossilized forests often comment on how similar their structure seems compared to modern day cypress swamps. It appears that warm, water-logged conditions present similar selection pressures today as they did 350+ million years ago.

Like all living things, scale trees eventually had to reproduce. From the tips of their dichotomosly branching stems emerged spore-bearing cones. The fact that they emerge from the growing tips of the branches suggests that each scale tree only got one shot at reproduction. Again, analyses of some fossilized scale tree forests suggests that these plants were monocarpic, meaning each plant died after a single reproductive event. In fact, fossilized remains of a scale tree forest in Illinois suggests that mass reproductive events may have been the standard for at least some species. Scale trees would all have established at around the same time, grown up together, and then reproduced and died en masse. Their death would have cleared the way for their developing offspring. What an experience that must have been for any insect flying around these ancient swamps.

Compared to modern day angiosperms, the habits of the various scale trees may seem a bit inefficient. Nonetheless, this was an extremely successful lineage of plants. Scale trees were the dominant players of the warm, humid, equatorial swamps. However, their dominance on the landscape may have actually been their downfall. In fact, scale trees may have helped bring about an ice age that marked the end of the Carboniferous.

You see, while plants were busy experimenting with building ever taller, more complex anatomies using compounds such as cellulose and lignin, the fungal communities of that time had not yet figured out how to digest them. As these trees grew into 100 ft monsters and died, more and more carbon was being tied up in plant tissues that simply weren’t decomposing. This lack of decomposition is why we humans have had so much Carboniferous coal available to us. It also meant that tons of CO2, a potent greenhouse gas, were being pulled out of the atmosphere millennia after millennia.

As atmospheric CO2 levels plummeted and continents continued to shift, the climate was growing more and more seasonal. This was bad news for the scale trees. All evidence suggests that they were not capable of keeping up with the changes that they themselves had a big part in bringing about. By the end of the Carboniferous, Earth had dipped into an ice age. Earth’s new climate regime appeared to be too much for the scale trees to handle and they were driven to extinction. The world they left behind was primed and ready for new players. The Permian would see a whole new set of plants take over the land and would set the stage for even more terrestrial life to explode onto the scene.

It is amazing to think that we owe much of our industrialized society to scale trees whose leaves captured CO2 and turned it into usable carbon so many millions of years ago. It seems oddly fitting that, thanks to us, scale trees are once again changing Earth’s climate. As we continue to pump Carboniferous CO2 into our atmosphere, one must stop to ask themselves which dominant organisms are most at risk from all of this recent climate change?

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

Further Reading: [1][2][3][4][5][6][7][8][9][10][11][12][13][14]

Biggest mass extinction caused by global warmi…

Biggest mass extinction caused by global warming leaving ocean animals gasping for breath:

“The signature of that kill mechanism, climate warming and oxygen loss, is this geographic pattern that’s predicted by the model and then discovered in the fossils,” Penn said. “The agreement between the two indicates this mechanism of climate warming and oxygen loss was a primary cause of the extinction.”

Australia Cuts 80% of Plastic Bag Use in 3 Sho…

We need the entire map to be red!

Australia Cuts 80% of Plastic Bag Use in 3 Short Months

Despite a few hiccups along the way, Australia’s plastic bag consumption has dropped drastically.

Three months after two of the largest supermarket chains banned plastic grocery bags, an estimated 1.5 billion bags have been prevented from use, the Australian Associated Press reported, citing the National Retail Association.

Overall, the bans introduced by Coles and Woolworths last summer resulted in an 80 percent reduction in the country’s overall use of the single-use item, the retail group revealed.

“Indeed, some retailers are reporting reduction rates as high as 90 per cent,” National Retail Association’s David Stout told the news service.