The Tiniest Flowers

It is easy to get caught up in grandeur. Finding the largest of something is always fun but what about the smallest? I have talked about the largest flowers in the world (http://on.fb.me/1bnfEbk) but how small can a flower get? The answer lies in one of the most common plants on earth, duckweed.

There are roughly 38 species of duckweed out there and all of them represent pretty much the epitome of flowering plant reductionism. They are little more than a pair or so of leaf-like structures that float at or near the waters surface and the occasional taproot. What is even more striking are the flowers. Whereas most duckweed will reproduce clonally, every once in a while a flower will be produced. One genus, Wolffia, produces the smallest flowers of any duckweed. They are also the smallest flowers known to science. As you can see from the picture, they are nothing more than a couple anthers (A1 and A2) and a pistil (Pi). What's more, the male parts mature and die before the female parts, thus limiting the chances of self fertilization. As one would expect, the fruits produced are also the smallest fruits in the world.

This is all quite interesting considering the fact that DNA analysis places duckweeds in the Araceae family, which is home to the largest single inflorescence in the world (http://on.fb.me/19i6XNX)! That's right, the arum family produces one of the largest groups of flowers in the world as well as the smallest flower and fruit in the world. Another cool fact about duckweed, specifically Wolffia, is that, gram for gram, it produces the same amount of protein as soy beans. Because of this, it is used as a food plant in many places around the world and more countries are waking up to its potential as both a food plant and a phytoremediation species. Pretty neat for such a small plant.

Photo Credit: Patrick Denny

Further Reading:

http://bit.ly/2c9smn9

http://bit.ly/2bPOMgX

http://bit.ly/2bPQw9A

http://bit.ly/2bzTL4I

Floating Ferns

Not every tiny plant you see growing on the surface of ponds are duckweeds. Sometimes they are Azolla. Believe it or not, these are tiny, floating ferns! The genus Azolla is comprised of about 7 to 11 different species, all of which are aquatic. Despite being quite small they nonetheless exert a massive influence wherever they grow. 

Like all ferns, Azolla reproduce via spores. Unlike more familiar ferns, however, sexual reproduction in Azolla consists of two markedly different types of spores. When conditions are right, little structures called "sporocarps" are formed underneath the branches. These produce one of two types of sporangia. Male sporangia are small and are often referred to as microspores whereas female sporangia are, relatively speaking, quite large and are referred to as megaspores. The resulting gametophytes develop within and never truly leave their respective spores. Instead, male gameotphytes release motile sperm into the water column and female gametophytes peak out of the megaspore to intercept them. Thus, fertilization is achieved. 

Azolla are fast growing plants. Via asexual reproduction, these little floating ferns can double their biomass every 3 to 10 days. That is a lot of plant matter in a short amount of time. As such, entire water bodies quickly become smothered by a fuzzy-looking carpet. Depending on the species and the environmental conditions, the color of this carpet can range from deep green to nearly burgundy. They are able to float because of their overlapping scale-like leaves, which trap air. Below each plant hangs a set of roots. The roots themselves form a symbiotic relationship with a type of cyanobacterium, which fixes atmospheric nitrogen. Couple with their astronomic growth rate, this means that colonies of Azolla quickly reach epic proportions.

They can grow so fast that Azolla may have played a serious role in a massive global cooling event that occurred some 50 million years ago. During that time, Earth was much warmer than it is now. In fact, global temperatures were so warm that tropical species such as palms grew all the way into the Arctic. There is fossil evidence that massive blooms of Azolla mau have occurred in the Arctic Ocean during this time, which was a lot less saline than it is now. Though plenty of other factors undoubtedly played a role, it is believed that Azolla blooms would have been so large that they would have drawn down CO2 levels considerably over thousands of years. As these blooms died they sank to the sea floor, bringing with them all of the carbon they had locked up in their cells. In part, this may have led to a massive drop in atmospheric CO2 levels and a subsequent cooling period. Evidence for this is tantalizing, so much so that some researchers have taken to calling this "The Azolla Event." However, this is far from a smoking gun. Regardless, it is an important reminder than really big things often come in very small packages.

Further Reading:

http://bit.ly/2c5c5zE

http://bit.ly/2c0DGD1

 

On the Wood Rose and its Bats

New Zealand has some weird nature. It is amazing to see what an island free of any major terrestrial predators can produce. Unfortunately, ever since humans found their way to this unique island, the ecology has suffered. One of the most unique plant and animal interactions in the world can be found on this archipelago but for how much longer is the question.

The story starts with a species of bat. In fact, this bat is New Zealand's only native terrestrial mammal. That's right, I said terrestrial. The New Zealand lesser short-tailed bat spends roughly 40% of its time foraging for insects on the ground. It has lots of specialized adaptations that I won't go into here but the cool part is they forage in packs, stirring up insects from the leaf litter until they reach a level of feeding frenzy that I thought was only reserved for sharks or piranhas. Along with using echo location, they also have a highly developed sense of smell. This is important for our second player in this forest floor drama.

Enter Dactylanthus taylorii, the wood rose. This plant is not a rose at all but rather a member of the tropical family Balanophoraceae. More importantly, it is parasitic. It produces no chlorophyll and lives most of its life wrapped around the roots of its host tree underground. Every once in a while a small patch of flowers break through the dirt and just barely peak above the leaf litter. This give this species it's Māori name of "pua o te reinga" or "pua reinga", which translates to "flower of the underworld." The flowers emit a musky, sweet smell that attracts these ground foraging bats. The bats are one of the only pollinators left on the island. They sniff out the flowers and dine on the nectar, all the while being dusted with pollen. Recently, it has been found that New Zealand's giant ground parrot, the kakapo, is also believed to have been a pollinator of this plant. Sadly, today the kakapo exists solely on one small island of the New Zealand archipelago.

Both the wood rose and the New Zealand lesser short-tailed bat are considered at risk for extinction. When modern man came to these islands they brought with them the general suite of mammalian invasives like rats, mongoose, cats, and pigs, which are exacting a major toll on the local ecology. The plants and animals native to New Zealand have not shared an evolutionary history with such aggressive mammalian invaders and thus have no adaptations for coping with their sudden presence. The future of the wood rose, the New Zealand lesser short-tailed bat, and the kakapo, along with many other uniquely New Zealand species are for now uncertain.

Photo Credits: Joseph Dalton Hooker (1859) and Nga Manu Nature Reserve (http://www.ngamanu.co.nz/)

Further Reading:

http://bit.ly/2bBw8FT

http://bit.ly/2bKRY90

http://bit.ly/2bKpxfE

The Devil's Walking Stick

The name "Devil's walking stick" just sounds cool. You can imagine my excitement then when I first laid eyes on the species it refers to. Aralia spinosa is no ordinary tree. It is a hardy species ready to take advantage of disturbance. Armed with spikes and a canopy that looks like it belongs in some far off tropical jungle, the Devil's walking stick is a tree species worth knowing. 

I used to think that spikenard (Aralia racemosa) was the most robust member of the aralia family found in North America. Not so. The Devil's walking stick is a medium sized tree capable of reaching heights of over 30 feet (10 m). Most interesting of all, its triply compound leaves are the largest leaves of any temperate tree in the continental United States. It can be found growing in disturbed areas and along forest edges throughout a large swatch of eastern North America. When young it is a rather spiny lot. These are not true spines, which are modified parts of leaves, but rather prickles, which arise from extensions of the cortex or epidermis. 

As it grows, however, it loses a lot of its prickliness. Such armaments are costly to produce after all. It is believed that younger plants develop these structures while they are still at convenient nibbling height only to lose them once they grow big enough to avoid hungry herbivores. Research has shown that most herbivorous mammals alive today do not bother much with the Devil's walking stick, which has led some to suggest that these defenses evolved back when this side of the continent was brimming with much larger herbivores such as elk and bison. 

Photo Credit: Celerylady - Wikimedia Commons

Photo Credit: Celerylady - Wikimedia Commons

As if the giant compound leaves of this tree were not stunning enough, the rather large inflorescence is sure to blow you away. Typical of the family, it consists of hundreds of tiny green flowers. Despite their size, they are a boon for pollinators. A tree in full bloom comes alive with bees and butterflies alike. Flowers soon give way to clusters of berries, which are a favorite food among birds. All in all this is one cool tree.

Further Reading:

http://bit.ly/2bjflW1

http://bit.ly/2bxgeye

Alien Plants

Confession: I am a huuuge science fiction nerd. That's right, when I am not reading and writing about botany or ecology, I like to unwind with the works of authors such as Arthur C. Clarke, Robert Heinlein, and David Gerrold. By and large my favorite sci fi topics are those dealing with aliens. Pondering alien ecology and culture is one of the best thought experiments. This obsession definitely bleeds into my day to day life. I have to admit that one of my greatest hopes is that we will discover life elsewhere in the universe. I'm not alone in this either. Many have devoted their careers to the search for extraterrestrial life. 

As any good scientist knows, we have to temper our expectations to the realm of reality. That being said, we have a very small sample size to base our expectations on. We only know of the carbon based life that we are part of. As such, this colors the way in which we think and search. Our search for habitable planets for instance takes into account all of the parameters that make Earth special. By looking for planets like ours, we are at least narrowing the possibilities to conditions we know can support life (as we know it). However, we can't let Earth be the only lens to color our search. That is where researchers such as Nancy Kiang come in. 

Nancy's work finds her modeling the conditions, both solar and atmospheric, of other planets in order to see which of them may be suitable for photosynthetic life. Certainly photosynthetic life isn't the only possibility out there but it sure is a good place to start. As on our planet, photosynthetic organisms are able to harness energy from the giant nuclear fusion reaction we call the Sun and turn that into food. However, not all suns are like ours. Alien "plants" may have to take advantage of stars very different from our own. 

This is where Nancy comes in. By modeling the conditions on the surface of hypothetical planets, she is able to identify the various wavelengths of energy that would be available to any organism primed to take advantage. For instance, the radiation given off by red dwarf stars would only provide a mere fraction of the visible light given off by our sun. "Plants" on a planet orbiting a red dwarf would need to absorb as much light as possible in order to photosynthesize properly. As such, these alien "plants" would likely appear black. 

Absorption is the key to this concept. The reason plants on Earth appear green is because that is the wavelength they do not absorb. Despite the fact that green light is the most abundant on our planet, it is quite weak in comparison to wavelengths of red and blue. Terrestrial plants absorb reds and blues and reflect green, which gives them their characteristic color. Because of this, Nancy and her team feel that it would be highly unlikely to find blue photosynthetic organisms elsewhere in the universe. Its simply too powerful a wavelength to not be utilized.

Still, until we find evidence of life on other planets, this is all a fun thought experiment. However, before you go writing off the work of researchers like Nancy Kiang as mere entertainment, remember that without such scientific speculation, we are left in the dark on exactly where and how to search for life elsewhere in the universe. By working out the possibilities of life on other planets, researchers like Nancy are helping to focus the search for extraterrestrial life. 

Photo Credit: Richard Mosse

Further Reading:

http://bit.ly/2bkQYbX

The Tallest Moss

For all the attributes we apply to the world of bryophytes, height is usually not one of them. That is, unless you are talking about the genus Dawsonia. Within this taxonomic grouping exists the tallest mosses in the world. Topping out around 60 cm (24 inches),  Dawsonia superba enjoys heights normally reserved for vascular plants. Although this may not seem like much to those who are more familiar with robust forbs and towering trees, height is not a trait that comes easy to mosses. To find out why, we must take a look at the interior workings of these lowly plants. 

Mosses as a whole lack the vascularization of more derived plants. In other words, they do not have the internal plumbing that can carry water to various tissues. Coupled with the lack of a cuticle, this means that mosses are quite sensitive to water loss. For most mosses, this anatomical feature relegates them to humid environments and/or a small stature. This is not the case for Dawsonia. Thanks to a curious case of convergent evolution, this genus breaks this physiological glass ceiling and reaches for the sky. 

Unlike other mosses, Dawsonia have a conduction system analogous to xylem and phloem. Being convergent, however, it isn't the same thing. Instead, the xylem-like tissue of these mosses is called the "hydrome" and is made up of cells called "hydroids." The phloem-like tissue is called the "leptome" and is made up of cells called "leptoids." These structures differ from xylem and phloem in that they are not lignified. Mosses never evolved the ability to produce this organic polymer. Regardless of their chemical makeup, Dawsonia vascular tissue allows water to move greater distances within the plant.

Another major adaption found in Dawsonia has to do with the structure of the leaves. Whereas the leaves of most mosses are only a few cells thick, the leaves of Dawsonia produce special cells on their surface called "lamella." These cells are analogous to the mesophyll cells in the leaves of vascular plants. They not only function to increase surface area and CO2 uptake, they also serve to maintain a humid layer of air within the leaf, further reducing water loss. 

All of this equates to a genus of moss that has reached considerable proportions. Sure, they are easily overtopped by most vascular plant species but that is missing the point. Through convergent evolution, mosses in the genus Dawsonia have independently evolved an anatomical strategy that has allowed it to do what no other extant groups of moss have done - grow tall. 

Photo Credits: Wikimedia Commons, Doug Beckers, and Jon Sullivan

Why Trees?

Walking through the forest is my favorite activity in the world. It is where I feel truly myself. There is something about towering trees that calms me. The thought of why forests are even there often jumps to mind during my strolls. Plenty of plants seem to do just fine hanging out closer to the ground. Why have trees (and some forbs) taken to this vertical realm. Why do forests exist?

In essence, forests are a prime example of an evolutionary arms race. It is one that these organisms have been fighting since the Devonian, roughly 385 million years ago. As plants left the water and began covering the land, some inevitably grew taller than others. There are pros and cons to growing tall. Competition is likely the prime driver for most tree species. Getting above your neighbors means more sunlight. Not every plant is as content as a fern to live out its life in the understory.

Height also means better pollinator visibility and seed dispersal for many tree species. Out in the open, gametes and propagules can be carried great distances by the wind. Eventually colorful blooms would prove to be more exposed and easier for pollinators to locate. Growing tall can also get you out of harms way, removing sensitive growing parts from many different kinds of hungry herbivores and all but the worst forest fires.

There are many downsides to growing tall as well. For one, trees are exposed to the elements and are often victims of strong winds or lightening strikes. What's more, all of that wood takes a lot of energy to produce and, at least for most species, gives nothing back in the way of photosynthesis. It is a rather hefty investment. However, the cost of getting shaded out by your neighbors is definitely not worth the risk of staying small for sun-loving species. Pumping water is another serious issue. The laws of physics suggest that redwoods are pushing the limits for how tall a tree can grow and still be able to lift water to leaves way up in the canopy. Of course, humidity can assist with such issues but for a majority of the water needs of a tree, water must be able to travel against gravity via weak hydrogen bonds. Water forms an unbroken chain within the vascular tissues of plants. As it evaporates from the leaves, it pulls more water up to fill in the void. It is possible that in today's world, a tree would not physically be able to grow much over 400 feet.

Despite the seemingly lavish waste of limited resources that a forest of trees would suggest, they are nonetheless a common occurrence all over the globe and have been for millions of years. The pros must certainly outweigh the cons or else tallness in trees would never have evolved. The next time you find yourself hiking through a forest, think of how the struggle for survival has led these towering organisms from lowly green stains on rocks to hulking behemoths racing towards the sky.

Further Reading:

http://bit.ly/2aXwNSB

http://go.nature.com/1Mrnh65

http://bit.ly/1xn7Qng

Freshwater Sponges

The first true love of my life was the underwater world. I was obsessed with everything aquatic, especially fish. My obsession with fish gave way to a collection of home aquaria that tested the limits of my parents patience. Most of my aquariums were landscaped with a variety of aquatic plants whose variety boggled the mind. The underwater world is full of incredibly varied habitats that are home to a myriad of different organisms. Entire ecological communities exist, often unnoticed, just under the waters surface. This fact was not lost on me this past week as I was paddling my way around the Bog River in the Adirondacks. One group of organisms that I became especially enamored with were the river's freshwater sponges.

Though it is not readily apparent, sponges are animals. They aren't a single animal either. What functions as a single unit is actually a collection of individual organisms working in unison. The entire body of the sponge consists of these microscopic individuals connected by living tissue and held rigid by tiny rods made out of silica. I know what you're thinking, this is not a plant, why am I writing about it? The answer lies in the green color of this sponge.

There are many species of freshwater sponge throughout the world. Here in North America we have somewhere around 30. They are an indicator of clean, clear water. If you see sponges then you know it must be a healthy ecosystem. The freshwater sponges come in many different shapes, colors and sizes. Even within a species there can be a lot of variety between each colony. Pictured here is a species of Spongilla. Not all Spongilla are green though. Many are brown. The green coloration comes from algae living symbiotically within the tissue of the sponge. Similar to lichens, the algae photosynthesize and provide food to the sponge in return for a safe place to grow.

Though not technically a plant, the need to photosynthesize has pushed these sponges to grow into shapes not unlike what is seen in the plant kingdom. Depending on water clarity, temperature, and light levels, sponge shapes range from prostrate, creeping forms to upright branching structures. Also similar to plants, sponges can reproduce both sexually and asexually. As the water begins to cool in the fall, the sponges produce what are known as gemmules. These little packets of dormant cells are quite hardy, resisting pretty much anything the environment can throw at them. When the water begins to warm in the spring, the gemmules will grow into new sponge colonies. During the warm summer months, sponges reproduce sexually. Males release sperm into the water in hopes that it will come into contact with receptive females. This is similar to what we see many wind pollinated tree species do in the spring.

The idea that two completely different branches on the tree of life have converged onto similar biological strategies is a very exciting idea. Indeed, the similarities are striking. I went a long time before I knew that these freshwater sponges even existed. The fact that I live in the Great Lakes region and never encountered them tells me just how poorly we have treated our local waterways.

Further Reading:

http://bit.ly/2aK2rSM

http://bit.ly/2b4jhOg

http://bit.ly/2aDHVle

http://bit.ly/2b6fGAt

The Amazing Radiation of Hawaii's Lobeliads

Hawai'i is home to so many interesting species of plants, many of which are found nowhere else in the world. One group, however, stands out among the rest in that it represents the largest plant radiation not just in Hawai'i but on any island archipelago in the world!

I am of course talking about the Hawaiian lobelioids. We are familiar with species found on North America, which include the lovely cardinal flower (Lobelia cardinalis) and the great blue lobelia (Lobelia siphilitica), but the 6 genera that comprise the Hawaiian radiation are something quite different altogether.

Numbering roughly 125 species in total (and many extinct species as well), it was long thought that they were the result of at least 3 separate invasions. Thanks to recent DNA analysis, it is now believed that all 6 genera are the result of one single invasion by a lobelia-like ancestor. This may seem ridiculous but, when you consider the fact that this invasion happened back when Gardner Pinnacles and French Frigate Shoals were actual islands and none of the extant islands were even in existence, then you can kind of grasp the time scales involved that produced such a drastic and varied radiation.

Sadly, like countless Hawaiian endemics, the invasion of the human species has spelled disaster. Hawaiian endemics are declining at an alarming rate. Introduced pigs and rats eat seeds, devour seedlings, and even go as far as to chew right through the stems of adult plants. To make matters worse, many species evolved to a specific suite of pollinators. Take the genus Clermontia for example. The flowers of these species are evolved for pollination by the island's endemic honey creepers. Due to avian malaria and other human impacts, many honey creepers are endangered and some have already gone extinct. Without their pollinators, many of these lobelioids are doomed to slow extinction if they haven't disappeared already. For some, what few populations remain are now fenced off and have to be hand pollinated. As I have said all too often, the future of this great radiation of plants is uncertain.

Photo Credits: Oakapples (http://bit.ly/OjOqhU), Forest and Kim Starr (http://bit.ly/1miCAA5), Dave Janas

Further Reading:

http://bit.ly/2aIviF5

http://bit.ly/2bh9Dpv

http://bit.ly/2b4i5dV

Albino Redwoods

If you are a very lucky person hiking in the redwood forests of California you may just be able to see a ghost. Not a "real" ghost of course, but pretty darn close. Scattered about these ancient forests are rare and peculiar albino redwood trees! Seeing one is seeing something very special indeed.

Redwoods (Sequoia sempervirens) are some of the largest and oldest organisms on the planet. They are famous worldwide for their grandeur. Aside from their obvious charismatic physical traits, redwoods are quite interesting genetically. These giant gymnosperms are genetically hexaploid, meaning they have 6 copies of their genetic code. What this means for redwoods is the ability to experiment with a wider array of mutations than a diploid organism like you and I. A mutation in one set of chromosomes still leaves 5 other copies to maintain normal genetic function. Whereas this can translate into massive benefits in defenses against pathogens, it also means there is a lot of room for error as well. 

The albino redwoods are an example of a seemingly dead end mutation. For a plant that relies of photosynthesis to survive, the loss of photosynthetic pigments should spell disaster. So then why do albino redwoods exist at all? The answer lies in the their ability to graft their roots with neighboring trees. The albinos become parasites on their normal photosynthetic neighbors. Researchers have found that the leaves of albino redwoods have twice the amount of stomata than do normal redwood leaves. This makes them quite susceptible to drought. During dry years, the trees quickly dehydrate and their host trees withdraw all support. The albinos will often die off but then re-sprout when conditions improve. This disappearing and reappearing act further lends to their mythos. 

There doesn't seem to be a solid consensus on how many albinos exist in the wild. I have seen numbers as low as 25 and as high as 100. Either way, they are a rare element of the coastal redwood community. With thousands of acres still to be explored, it is likely that more will turn up. While some exist in protected parks, many are under threat with increasing fragmentation of these ancient forests. Very little of the coastal redwood forests are under protection and we may be losing more than we will ever know. 

Photo Credit: Cole Shatto and George Bruder

Further Reading:

http://bit.ly/1kBglE8

http://reut.rs/2aSFaz3

In the Wake of Volcanoes

Recruitment windows are a crucial component of of any plants lifecycle. For some species, these windows are huge, allowing them ample opportunity for successful reproduction. For others, however, these windows are small and specific. Take for instance the saguaro cactus (Carnegiea gigantea) of the American southwest. The arborescent cacti are famous the world over as icons of the desert. They are true survivors, magnificently adapted to their harsh, dry environment. This does not mean life is a cakewalk though. Survival, especially within the first year, is measured by the slimmest of margins, with most saguaro dying in their first year. 

Hot, dry days and freezing cold nights are not particularly favorable conditions for young cacti. As such, any favorable change in weather can lead to much higher rates of successful recruitment for a given year. Because of this, saguaro often grow up as cohorts that all took advantage of the same favorable conditions that tipped the odds in their favor. This creates an age pattern that researchers can then use to better understand the dynamics of these cacti. 

Recently, a researcher from York University noticed a particular pattern in the cacti she was studying. A large amount of the older cacti all dated back to the year 1884. What was so special about 1884? Certainly the climate must have been favorable. However, the real interesting part of this is what happen the year before. 1883 saw the eruption of Krakatoa, a volcanic island located between Java and Sumatra. The eruption was massive, spewing tons of volcanic ash into the air. Effectively destroying the island, the eruption was heard 1,930 miles away in western Australia. 

The effects of the Krakatoa eruption were felt worldwide. Ash and other gases spewed into the atmosphere caused a chilling of the northern hemisphere. Records of that time show an overall cooling effect of more than 2 degrees Fahrenheit. In the American Southwest, this led to record rainfall from July 1883 to June 1884. The combination of higher than average rainfall and lower than average temperatures made for a banner year for saguaro cacti. Seedlings were able to get past that first year bottleneck. After that first year, the saguaro are much more likely to survive the hardships of their habitat. 

The Krakatoa eruption wasn't the only one with its own saguaro cohort. Further investigations have revealed similar patterns following the eruptions of Soufriere, Mt. Pelée, and Santa Maria in 1902, Ksudach in 1907, and Katmai in 1912. What this means is that conservation of species like the saguaro must take into account factors far beyond their immediate environment. Such patterns are likely not unique to saguaro either. The Earth functions as a biosphere and the lines we use to define the world around us can become quite blurry. If anything, this research underlines the importance of a system based view. Nothing operates in a vacuum. 

Photo Credit: Geir K. Edland

Further Reading:

http://bit.ly/2anyKba

http://bit.ly/2amf5Lx

The Mountain Sweet Pepperbush

This first thing I noticed about the mountain sweet pepperbush (Clethra acuminata) was its bark. There before me was a lanky looking tree with beautiful cinnamon-colored bark that peeled back in thin sheets. The effect was a mottle appearance that didn't seem right for where I was hiking. A closer inspection revealed spikes of flower buds that were weeks away from blooming. This was a species I was going to have to keep my eyes on. 

The mountain sweet pepperbush (sometimes called cinnamonbark) is native to a small chunk of eastern North America from Pennsylvania down into Georgia and Alabama. It enjoys acidic, rocky soils and is perfectly at home in the Appalachian Mountains. It isn't a large tree, topping out around 20 feet or so but what it lacks in stature it makes up for in beauty. 

Come mid summer the long spikes put forth a spray of beautiful white flowers. The trees come alive with pollinators to the point that you can literally hear them humming. Though it may not be apparent, the genus Clethra is a distant relative of the heath family. However, taxonomists find it distinct enough to warrant its own family, Clethraceae. Regardless of its taxonomic affinity, this is one tree that needs to find its way into native landscaping. It is such a stunning plant and does well in in both shade and full sun. Few trees are as stunning to come across on a hike than this one and its a species I will look fondly upon for the rest of my life. 

Further Reading:

http://plants.usda.gov/core/profile?symbol=CLAC3

Brother of Hibiscus

Islands are known for their interesting flora and fauna. Until humans came on the scene, colonization events by different species on different islands were probably rare events, with long stretches of time in between. Because of this, islands are interesting experiments in evolution, often having endemic species found nowhere else in the world. Hawai'i was once home to many different kinds of endemic species. One such group are the Hibiscadelphus.

As you may have gathered by the name, Hibiscadelphus is a relative of hibiscus. The Latin name means "brother of Hibiscus." Unlike the widely splayed flowers of their relatives, Hibiscadelphus flowers never fully open. Instead, they form a tubular structure with a curved lower lip. The genus consists of 7 species. Four of these have gone completely extinct, two are only maintained in cultivation, and the remainder is barely holding on. There have been attempts to reestablish some species into other portions of their range but due to hybridization, these attempts were ceased. In my opinion this is a shame. In this case, a hybrid is better than losing both parental species and it would still be uniquely Hawaiian.

Why are Hibiscadelphus so rare? Well, humans have a sad history when it comes to colonizing islands. They bring with them a multitude of invasive species at a rate in which the local flora and fauna cannot adapt. They change the land through cultivation and development as well as by subduing natural fire regimes. Also, they wipe out keystone species, which causes a ripple effect throughout the environment. Hibiscadelphus have faced all of these threats and more. Pigs and rats eat their seeds, their habitats have been turned over for the ever-increasing human population, fires have been stopped, and some of their pollinators, the endemic honeycreepers, have also been driven to extinction thanks to avian pox and malaria. Sadly, this is a story that repeats itself time and time again all over the world. For now, the future of Hibiscadelphus is rather bleak.

Photo Credit: David Eickhoff

Further Reading:

http://bit.ly/2ao84X1

http://bit.ly/2aEfpkn

Yeast in Lichens

Quite possibly one of the oldest symbiotic relationships on Earth has been hiding in plain sight all this time. Lichens have long been regarded as the poster child for symbiotic relationships. Certain species of fungi team up with specific algae and/or cyanobacteria in a sort of "you scratch my back and I'll scratch yours" type of relationship. In return for room and board the photosynthetic partner feeds the fungus. There are many variations on this theme which translates into the myriad shapes and colors of lichen species around the globe. For 150 years we have been operating under the assumption that there is only ever one species of fungus (in the phylum Ascomycota) for any given lichen. We were wrong. 

Originally thought to be contamination, researchers at the University of Montana and Perdue found gene expression belonging to the other major fungal phyla, Basidiomycota. The research team soon realized that they had uncovered something quite monumental. Lichens were harboring a partner we never knew existed. These newly discovered fungi are an entirely new lineage of yeast. What's more, this relationship has been documented in upwards of 52 other lichen genera worldwide! 

This discovery has led to another major breakthrough in lichen biology, their bizarre variety. The exact same species of fungus and alga can produce completely different lichens with wildly different attributes. Take the example of Bryoria torturosa and B. fremontii. They were thought to share the same partners and yet one is yellow and toxic whereas the other is brown and innocuous. Knowing what to look for, however, has revealed that their yeast partners are entirely different. The yeast is thought to be a sort of shield for the lichen, producing noxious acids that deter infections and predation. 

Almost overnight a new light has been shown on our lichen neighbors. These newly discovered partners aren't a recent evolutionary development. This trifecta likely stems back to the early days when little else lived on land. It just goes to show you how much we still do not know about our planet. It's nice to be reminded of this. 

Further Reading:

http://bit.ly/29WWZ2z 

The Cranefly Orchid (Tipularia discolor)

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Look closely or you might miss it. Heck, even with close inspection you still run the risk of overlooking it. At this time of year, finding a cranefly orchid (Tipularia discolor) can present a bit of a challenge. At other times of the year the task is a bit easier. If you can find one in bloom, however, you are rewarded with, in my opinion, one of the most unique terrestrial orchids in temperate North America.

For most of the year, the cranefly orchid exists as a single leaf, which is produced in the fall and lasts until spring. It is thought that this orchid takes advantage of the dormancy of its neighbors by sucking up the light the canopy otherwise intercepts during the growing season. Any of you curious enough to look will have noticed that the underside of this leaf is deep purple in color. This very well may be an adaptation to take full advantage of light when it is available. There is some evidence that such coloration may help reflect light back up into the leaf, thus getting more out of what makes it to the forest floor. Evidence for this, however, is limited. It is far more likely that the purple coloration are pigments produced by the leaves that act as a sort of sun screen, shielding the sensitive photosynthetic machinery within from an overdose of sun.

By the end of spring, the single leaf has senesced. If energy stores were ample that year the plant will then flower. A lanky brown spike erupts from the ground. Its purple-green color is subtle yet beautiful. The flowers themselves are a bit odd, even by orchid standards. Whereas most orchid flowers exhibit satisfying bilateral symmetry, the flowers of the cranefly orchid are distinctly asymmetrical. The dorsal sepal, along with the lateral petals, are scrunched up on either side of the column. This has everything to do with its pollinators.

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The cranefly orchid has coopted nocturnal moths in the family Noctuidae for pollination. These moths find the flowers soon after they open and stick around only as long as there is nectar still present in the long nectar spurs. The asymmetry of the bloom causes the pollinia to attach to one of the moth's eyes. In this way the orchid is able to ensure that its pollen is not wasted on the blooms of other species.

As in all plants, the production of flowers is a costly business. Sexual reproduction is all about tradeoffs. It has been found that cranefly orchids that flowered and successfully produced fruit in one year were much less likely to do so in the next. What's more, the overall size of the plant (leaves and corms) were greatly reduced. Its hard to eek out an existence on the forest floor.

What I find most interesting about this species is where it tends to grow. Any old patch of ground simply won't do. Research indicates that the cranefly orchid requires rotting wood as a substrate. It's not so much the wood they require but rather the organisms that are decomposing it. Like all orchids, the cranefly cannot germinate and grow without mycorrhizal associations. They just happen to partner with fungi that also decompose wood. Such a relationship underscores the importance of decaying wood to forest health.

Further Reading:
http://bit.ly/29RSylm

http://bit.ly/29MAEz7

http://bit.ly/29K3UdZ

http://bit.ly/29WAycl

http://bit.ly/2a6fO19

Meeting Amborella trichopoda

When I found out I would be seeing a living Amborella, a lump formed in my throat. There I was standing in one of the tropical houses at the Atlanta Botanical Garden trying to keep my cool. No amount of patience was ample enough to quell my excitement. How was I going to react? How big were these plants? Would I see flowers? Could I touch them? What were they growing in? My curiosity was through the roof.

Naturally this sort of excitement is reserved for those of us familiar with Amborella trichopoda. This strange shrub is not something that would readily stand out against a backdrop of tropical flora. However, if life history and ecology were to be translated into outward appearances, Amborella would likely be one of the most gaudy plants on this planet. What I was about the lay eyes on is the only member of the sole genus belonging to the family Amborellaceae, which is the sole member of the order Amborellales.

Even more exciting is its position on the angiosperm family tree. As flowering plants go, Amborella is thought to be the oldest alive today. Okay, so maybe this shrub isn't the oldest flowering plant in the world. It is likely that at one time, many millions of years ago, there were more representatives of Amborellaceae growing on this planet. Until we turn up more fossil evidence it is nearly impossible to say. Still, Amborella's place in the story of flowering plant evolution is consistently located at the base.

That is not to say that this shrub is by any means primitive. I think the first thing that shocked me about these plants is just how "normal" they appear. Sans flowers, I didn't see much out of the ordinary about them. They certainly look like they belong on our timeline. Without proper training in plant anatomy and physiology, there is little one could deduce about their evolutionary position. Regardless of my ignorance on plant morphology, there is plenty to look at on Amborella.

For starters, Amborella has tracheids but no vessel elements, making its vascular system more like that of a gymnosperm than an angiosperm. Its small flowers are borne in the axils of the evergreen leaves. It has no petals, only bracts arranged into a spiral of tepals. The female flowers consist of 4 to 8 free carpels and do not produce a style. Male flowers look like nothing more than a spiral cluster of stamens borne on short filaments.

If plant anatomy isn't enough to convince you, then the genetic analyses tell a much more compelling story. DNA sequencing consistently places Amborella at the base of the flowering plant family tree. Again, this is not to say that this shrub is by any means "primitive" but rather its lineage diverged long before what we would readily recognize as a flowering plant evolved. As such, Amborella offers us a window into the early days of flowering plants. By comparing traits present in more derived angiosperms to those of Amborella, researchers are able to better understand how the most dominant group of plants found their place in this world.

Another interesting thing happened when researchers looked at the DNA of Amborella. What they found was more than just Amborella genes. Inside the mitochondrial DNA are an unprecedented amount of foreign DNA from algae, lichens and mosses. In fact, an entire chunk of DNA corresponded to an entire mitochondrial genome of a moss! Researchers now believe that this is a case of extreme horizontal gene transfer between Amborella and its neighbors both growing on and around it. Both in the wild and in cultivation, Amborella is covered in a sort of "biofilm." Whether or not such gene transfer has assisted in the conservatism of this lineage over time remains to be seen.

At this point you may be asking how this lineage has persisted for over 130 million years. For the most part, it is probably due to chance. However, there is one aspect of its ecology that really stands out in this debate and that is its geographic distribution. Amborella is endemic to Grande Terre, the main island of New Caledonia. This is a very special place for biodiversity.

New Caledonia is a small fragment of the once great super-continent Gondwana. New Caledonia, which was part of Australia at that time, broke away from Gondwana when the super-continent began to break up some 200-180 million years ago. New Caledonia then broke away from Australia some 66 million years ago and has not been connected to another land mass since. A warm, stable climate has allowed some of the most unique flora and fauna to persist for all that time. Amborella is but one of the myriad endemic plants that call New Caledonia home. For instance, 43 species of tropical conifers that grow on these small islands are found nowhere else in the world. The whole region is a refugia of a long lost world.

Being a biodiversity hot spot has not spared New Caledonia from the threats of modern man. Mining, agriculture, urbanization, and climate change are all threatening to undo much of what makes this place so unique. The loss of a species like Amborella would be a serious blow to biodiversity, conservation, and the world as whole. We cannot allow this species to exist only in cultivation. New Caledonia is one place we must desperately try to conserve. Meeting this species has left a mark on me. Being able to observe living Amborella up close and personal is something I will never forget as my chances of seeing this species in the wild are quite slim. I am so happy to know that places like the Atlanta Botanical Garden are committed to understanding and conserving this species both in the wild and in cultivation. For now Amborella is here to stay. Long may it be that way.

 

Further Reading:

http://bit.ly/29MuMuw

http://bit.ly/29MuML0

http://bit.ly/29ZKNJS

 

Sequential Ripening

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There are few things better than hiking on a hot summer day and coming across a big patch of ripe blackberries and/or raspberries. If you're anything like me then you promptly gorge yourself on handfuls of these sweet aggregate fruits. However, the genus Rubus never gives its fruit away all at once. Although this may seem like a pain for us humans, there is good reason for it.

The answer to this ripening strategy lies in the seed dispersers. A multitude of animals feed on the fruit of the genus Rubus but by and large the best seed dispersers are birds. Rubus fruits begin to ripen around the time when many birds are beginning to ramp up their food intake to prep for either migration or the long winter to come. Regardless, birds can travel great distances and thus can spread seeds via their droppings wherever they go.

If Rubus were to ripen their fruit all at once, only a handful of birds would make use of the entire seasons reproductive effort. This means that all the seeds of an individual plant would likely fall to the ground in the general vicinity of the parent. By sequentially ripening their fruit, Rubus ensure that their seeds will not only be available for a few weeks to a couple of months, it also ensures that birds, as well as many other animals, will be involved in the distribution of seeds. It's not just the genus Rubus that does this either. Plenty of other berry producing plants ripen their fruitss sequentially. It is a wonderfully successful strategy to persuade mobile organisms to do exactly what the plants require. 

Photo Credit: Nicholas A. Tonelli (http://bit.ly/1q6Gvja)

Further Reading:
http://bit.ly/29ghcwL

The Mountain Pitcher Plant

I am fascinated by pitcher plants. The myriad shapes, sizes, and colors make them quite a spectacle. Add to that their carnivorous habit and what is not to love? I am used to having to visit bogs or coastlines to see them in person so you can imagine my surprise to learn that a small handful of pitcher plants haunt the mountains of Southern Appalachia. 

Sarracenia jonesii is a recent acquaintance of mine. I never knew this species existed until last year. It is a slender pitcher plant whose traps grow taller and narrower than the purple pitcher plant (S. purpurea) but not nearly as tall and robust as species like S. leucophylla. Regardless of its size, this one interesting pitcher plant. One of the most unique aspects of its ecology is the habitats in which it grows. What could be more strange than a pitcher plant clinging to sloping granite slabs?

Most mountainous areas don't hold water for very long. Aside from bowls and the occasional lake, gravity makes short work of standing water. In Southern Appalachia, this often results in impressive cascades where sheets of water flow over granite. Where water moves slow enough to not wash soil and moss away, cataract bogs can form. Soils are so thin in these areas that trees and shrubs can't form, thus keeping competition to a minimum. Because granite is rather inert, nutrients are scarce. All of these factors combine to make prime carnivorous plant habitat. 

Along the edges of these cataract bogs and anywhere sphagnum and other mosses grow is where S. jonesii finds a home. One would think that growing in such hard to reach places would protect this interesting and unique carnivore. Sadly, that is not the case. To start with, S. jonesii was never common to begin with. Native to a small region of North and South Carolina, it is now only found in about 10 locations. 

Habitat destruction both direct and indirect (alterations in hydrology) has taken its toll on its numbers in the wild. To add insult to injury, poaching has become a serious issue. In fact, an all green population of this species was completely wiped out by greedy collectors looking to add something rare to their collections. The good news is that there are dedicated folks working on conserving and reintroducing this plant into the wild. In 2007, conservationists at Meadowview Biological Research Station, with help from the National Fish and Wildlife Foundation Grant, successfully reintroduced a population of S. jonesii to its former range. 

Although the future remains uncertain for this species, it nonetheless has captured hearts and minds alike. Hopefully the charismatic nature of this species is enough to save it from extinction. I only wish such dedicated conservation efforts were directed at more imperiled plant species, both charismatic and not. 

Further Reading:

http://bit.ly/29fyTd3

http://bit.ly/29Mo43V

http://bit.ly/29vk23j

On Native Loosestrife and Oil Bees

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Oil bees? What the heck is an oil bee? Those were my first thoughts when I heard of them for the first time. There are something like 320 species of oil bee in this world and they have very interesting ecologies. These solitary insects seek out certain flowers that produce special oils that the bees mix with pollen to feed their developing young. Some even go as far as to use the oils to line their nests. 

Surely these bees must be tropical. I really couldn't imagine this interaction going on up here in the temperate zones. You can imagine my surprise then when I found that there are oil bees and the plants they require haunting some of my favorite hiking spots. As it turns out, the genus Lysimachia is comprised of many different flowering plant species that produce these oils. 

What's more, the bees that utilize them are quite specialized. They all hail from the same genus - Macropis. These bees dig their nests into the ground. Using their highly tuned senses, these little solitary oil bees search far and wide for species of loosestrife that can provide the oils they need. The whorled loosestrife (Lysimachia quadrifolia) is one such species. If you look closely, you can see that the inside of the flowers are streaked with dark resin canals. 

Luckily for the oil bees, this species seems to be quite adaptable as far as habitat goes. I see it most often lining trails and service roads. Mature plants create quite the spectacle with their tall stature, whorled leaves, and sprays of yellow flowers. I will have to pay close attention to these blooms over the next couple of weeks in hopes of seeing the oil bees that share such a close relationship with it. 

Further Reading:
http://bit.ly/28K9k8d

http://bit.ly/28Ks2vV

One Hardy Shrub

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One would be hard pressed to find a native shrub with as much adaptability as the dwarf bush honeysuckle (Diervilla lonicera). It is a wide ranging species growing From Saskatchewan to Labrador in Canada all the way down into Georgia. Though it is most often encountered growing on rocky outcrops in the wild, it seems to do equally well under more mesic conditions. It grows rapidly and seems quite fond of suckering. As such, it is an excellent plant for erosion control. 

It is also an important species from an ecological perspective. Many species find this shrub quite appetizing. Its aggressive suckering habitat may be in response to such palatability as it seems to respond to browsing with increased vigor. Its thick growth form is excellent for nesting birds as well as any animal looking for shelter. 

As if cover and browse wasn't enough, the flowers of the dwarf bush honeysuckle are a boon for pollinators far and wide. Flowers range in color from red to yellow and they are accessible enough that many different pollinators benefit from their nectar and pollen rewards. Bumblebees seem to benefit the most from these blooms. It is a real joy to watch a large population of this shrub literally humming with bees. 

Further Reading:

http://bit.ly/29kefyw

http://bit.ly/29iuqac