Mountainsides awash with blooming mountain laurel (Kalmia latifolia) are truly a spectacle. Seeing a sea of pinks, whites, and greens humming with pollinators makes you wonder why such a sight isn't talked about more outside of its range. Why hoards of tourists don't time their seasonal migrations around the blooming of this species is, to me, quite a mystery.
Mountain laurel was a shrub I was quite familiar with growing up. As a child, their shaded tunnel-like understory were some of my favorite places to explore and catch bugs. After moving to New York, I soon forgot about this shrub. Other species became my familiar backdrop. It took visiting the mountains of North Carolina to reawaken these long forgotten memories.
Mountain laurel is generally considered a shrub. In wet, humid areas in the Appalachians, they can readily reach a stature more fitting of a small tree. They are evergreen, holding on to their beautiful leaves throughout the winter. This helps save energy, which is especially useful in poor soils. It also allows mountain laurel to get a head start on photosynthesis as soon as temperatures become favorable.
My favorite part of this shrub are its flowers. Deep pink textured buds soon give way to a floral display that will knock your socks off. Each flower ranges in color from white to pink. Each bloom demands a closer inspection. They are ringed in tiny pockets, each housing an anther. As the flower opens, the pockets hold on to the anthers, drawing them tight. When an insect, especially a bee, disrupts the pockets, the anthers spring out of the pockets and bash the insect with pollen. Each visit is like stumbling into a army of tiny pollen-laden trebuchets. This can easily be simulated using a small stick.
Further Reading:
http://bit.ly/25eAwzI
Spring Surprise on the Tallgrass Prairie
I have no frame of reference for spring on the tallgrass prairie. Everything is new to me. It is amazing to see what starts to come up before all of the grasses wake up and make things a lot harder to find. Diminutive herbs take advantage of sunlight while they can. What I also like is how well certain species stand out against a backdrop of last year's dry stems. This is how I was able to find wild hyacinth (Camassia scilloides).
The first time I laid eyes on this species, I was actually looking for birds. The spot I was in is known for harboring pheasants. I could hear the males calling but I was having a hard time locating these colorful birds. As I scanned the prairie for shots of color, something else caught my eye. From where I was standing, it looked like a green stick covered in foam. I couldn't quite make out enough detail. I knew it had to be a plant but the search imagine simply wasn't there. I had to investigate.
Gingerly I tip toed out into the grasses trying to avoid stepping on emerging vegetation. Luckily some deer had already beat a path pretty close to where this mystery plant was growing. When I was only a few yards away I quickly realized what I was seeing. It was a small patch of wild hyacinth. From a distance it was hard to resolve the outline of the tightly packed flowers. From up close, however, it is one of the most stunning spring displays I have ever seen.
They were covered in ants. As it turns out, these flowers produce copious amounts of nectar. Whereas ants offer nothing in the way of pollination, myriad other insects like flies, bees, butterflies, and wasps visit these blooms in search of a sweet, energy-rich meal. This plant seems to have no trouble getting pollinated. This is a spring species, emerging from an underground bulb not unlike the hyacinths you buy at nurseries. It has slender, grass-like foliage that isn't always apparent mixed in with all of the other vegetation.
I was a little surprised that such an obvious plant could exist unharmed so near a deer path until I did some research. Like many of its relatives, wild hyacinth is quite toxic to mammals. As such, the deer were smart to pass it up. After years of seeing nothing but its introduced Asian relatives, I was quite happy to be meeting an eastern species native to North America.
Further Reading:
North America's Native Peonies
Brown's peony (Paeonia brownii). Photo by Mathesont licensed under CC BY-NC 2.0
Foliage of Brown's peony (Paeonia brownii). Photo by jacki-dee licensed under CC BY-NC-ND 2.0
Brown's peony (Paeonia brownii). Photo by Jim Morefield licensed under CC BY-SA 2.0
Whereas most species of peony are Eurasian in decent, there are two species of peony that are native to North America. Brown's peony (Paeonia brownii) inhabits high elevation regions of most of northwestern North America. The California peony (Paeonia californica) has a much narrower range, limited to southwestern California. Some feel it should be considered a subspecies of P. brownii. While not as showy as their Eurasian cousins, they are nonetheless quite interesting plants!
California peony (Paeonia californica). Photo by Dagmar Collins licensed under CC BY-NC-ND 2.0
California peony (Paeonia californica). Photo by Justin Meissen licensed under CC BY-SA 2.0
California peony (Paeonia californica). Photo by Teddy Llovet licensed under CC BY 2.0
Photo Credits: [1] [2] [3] [4] [5] [6]
Further Reading:
http://plants.usda.gov/core/profile?symbol=PACA2
An Awesome Ophioglossum
Sometimes I wonder how I must look to casual hikers. There I was sprawled out next to the trail, focusing all of my attention on a nondescript patch of leaves poking up where the trail ended and the grass began. This wasn't just any sort of leaf though. The object of my attention was an ancient member of the fern lineage commonly referred to as an adder's tongue. I will gladly look like a weirdo if it means spending time in the presence of such a cool plant.
To be more specific, the species in question here is the southern adder's tongue (Ophioglossum pychnostichum). Though not overtly showy like its more derived cousins, this little fern is nonetheless quite the show stopper if you know what you're looking for. It is generally considered a grassland associate and is most often encountered growing alongside trails. I'm not sure if this has to do with some disturbance related factor or the fact that even modestly sized plants can overshadow it.
Regardless, I felt very fortunate to be in the presence of at least one reproductive individual. For much of its life, the southern adder's tongue exists as a gametophyte followed by an underground fleshy rhizome. It can exist in this state for years, being nourished solely by an obligate association with mycorrhizal fungi. When a certain energy threshold is reached, individuals will then produce a single, sterile leaf. This can go on for season after season as the fern slowly stores away nutrients. When enough energy has been stored, mature individuals can then produce a spore bearing structure called a "sporophyll."
Despite its common name, this particular species distributed throughout the Northern Hemisphere. It can be found growing in North America, Europe, and temperate Asia. Still, since it is such a nondescript little plant, it rarely gets the attention it deserves when it comes to conservation. It is of conservation concern in at least a handful of states. Because its lifecycle can be hard to predict, growing some years and not others, accurate estimates of population size and health can be difficult.
The family to which is belongs is quite interesting on a genetic level as well. Ophioglossaceae is known for having staggeringly large chromosome counts. One species in particular - Ophioglossum reticulatum - boasts a whopping set of 1260 chromosomes. To put that into perspective, we humans only have 46. I guess thats what can happen to a genome that has had millions upon millions of years of natural selection working upon it.
Further Reading:
What is the Most Common Flower Color?
Photo by Mor licensed under CC BY-NC 2.0
Have you ever wondered what the most common flower color is? If one were to tally up all the known flowering plants, what color or colors would come out on top? I have pondered this time and again and I for some reason have a bias towards yellow. I think it is a symptom of where I live. In fact, I think flower color in general can, in part, be considered a function of geographic location. Each region of the world has its own specific pollinators driving selection for flower color. I decided to finally try and track down an answer to this question.
The truth of the matter is, no one really knows. There is simply no database out there that fully characterizes all the colors flowers can be, let alone rank them by abundance. When you really think about it in the context of real world examples, it makes sense that this would be a daunting task. The first question becomes "how do we define the color of a flower?" This may seem silly but think about it. How many times has a field guide said one thing and reality says another? This is the main reason I don't use Peterson's Field Guide to Wildflowers. Colors vary from genus to genus and heck, they even vary within a species. A plant growing in one area may look one way while the same species growing in another area can look totally different. Far from being simply a function of genes, flower color can be just as dependent on growing conditions.
Also, what one botanist calls red may not be what everyone else calls red. Barring a persons ability to see all of the visible light spectrum, there is no set standard, for flowers at least, as to where we draw the lines between colors. What we end up with at the end of the day are lumped packages of color pertaining to a chunk of the spectrum visible to us. It is actually an easier question to ask "what is the rarest flower color?" To that, most botanists will probably say black. To the best of my knowledge, there is only one species of plant in the world with truly black flowers. The rest are more accurately deep shades of red or purple. True blue is another rare color among flowers for the same reason.
After a few hours (more than I should have dedicated to the cause) I came up with one satisfying answer and to sum it all up, I will put it this way: We simply have no idea what the most common flower color is in the world but it's probably green. We tend to only pay attention to the showiest flowers. Big or small, we like bright colors and we like weird colors. All the rest just get glazed over. In reality, many plant species, especially trees, produce small, non-descript green flowers. For this reason I would say that green is a safe default until someone or a group of someones puts in the time that would be needed to put any meaningful numbers to this inquiry.
Photo Credit: Mor (http://bit.ly/1y0WnJd)
Anise: An Angiosperm Success Story
Illicium floridanum Photo by Scott Zona licensed under CC BY-NC 2.0
I must admit there are few flavors I loath more than anise (and consequently licorice and fennel). Regardless of the flavor, I nonetheless find myself enamored by their whorled seed capsules of star anise. In an attempt to reconcile my feelings towards anise in a culinary sense, I decided to get to know the plants that are responsible for it and I am so glad that I did. As it turns out, this group of small trees and shrubs offer us a glimpse at some of the earliest branchings on the angiosperm family tree.
We get star anise from the genus Illicium. Native to humid tropical understories, there are roughly 40 species scattered around southeast Asia, southeastern North America, the Caribbean, and parts of Mexico. Molecular as well as fossil evidence suggests this group diverged during the mid to late Cretaceous, not long after flowering plants came onto the scene. Indeed, along with Amborella and Nymphaeales, Illicium represent the three lineages that are sister to all other flowering plants alive today.
Illicium henryi Photo by Scott Zona licensed under CC BY-NC 2.0
To call them primitive, however, would be a serious misnomer. Because they diverged so early on, these lineages represent serious success stories in flowering plant evolution. Instead, think of them as fruitful early experiments in angiosperm evolution. Illicium has characteristics that set it out as being sister to all other flowering plants. For instance, the vascular tissues more closely resemble those of gymnosperms than they do angiosperms. Also, like the other sister angiosperms, Illicium blur the line between the long standing categories of monocot and eudicot. As such, they are sometimes referred to as "paleoherbs." Another key diagnostic feature lies in their floral morphology.
They don't have what could be considered true petals or sepals. Instead, they have whorls of tepals, which start off sepal-like and gradually become more petal-like as you near the center of the flower. The stamens, which are laminar or leaf-like, are also arranged in a dense whorl surrounding a yet another whorl of fused carpels. Once fertilized, each carpel gives rise to a hard, glossy seed. As the carpels mature and begin to dry, the individual capsules get tighter and tighter until at some point the seed is pinched so hard that it is ejected from a slit in the fruit in projectile fashion.
Illicium verum. Photo by Tim Waters licensed under CC BY-NC-ND 2.0
Although this research will never rectify the taste of this spice, it nonetheless has given me a new found respect and sense of awe for this genus. To look upon the fruit of Illicium is to look at a biological structure that has stood the test of time. These plants are evolutionary successes that should be admired for their unique place in the story of flowering plant evolution.
Photo Credits: Scott Zona and Tim Waters
Further Reading: [1]
Why Trees Have Rings (and why they are so useful)
Dendrochronology is a field of study that focuses on tree rings. Though it may not be obvious, the amount of information we gain from looking at these rings is astounding. This research goes far deeper than simply finding out how old a tree was when it died. Dendrochronological data can be used to investigate paleoclimates, paleoecologies, and the archaeological dating of buildings and artwork. It is amazing how a practiced eye can look back in time. To date, we have an unbroken dendrochronological record for the northern hemisphere dating back some 12,000+ years!
All of this would not be possible if it were not for tree rings. But what exactly are they and how do they form? The answer is physiological. Essentially tree rings result from patterns in vascular tissues. Early in the spring, before the leaves start to grow, a layer of tissue just under the bark called the cambium begins to divide. In this cool, water-laden time of the growing season the vessels that are produced are large and less dense. This is the beginning of the spring or early wood. Although they are not as strong as vessels that are produced later in the season, they sure can move a lot of water. Things are a bit different for conifers. Because they do not produce vessel elements in their wood, this large cell growth is initiated instead by large amounts of a growth hormone called auxin that is produced by the new buds. This causes the cells of the early wood in conifers to grow large in a similar way to that of the hardwoods.
As summer heats up, things start to change. The cambium starts producing smaller, thicker cells. The vessels that result from this are much stronger than those of the early wood. This late wood as it is called gives trees much of their rigidity and strength. Late wood is also resistant to what is called cavitation, a process in which water within the tree can literally vaporize, causing a damaging embolism during the hottest months of summer. In conifers, bud growth stops by mid to late summer and with it much of the production of auxin. This results in smaller vessels as well.
In temperate regions, this cycle of growth occurs over the course of a growing season. As such, each ring demarcates a year in that trees life. Because so much of a trees growth is determined by environmental conditions, the size and shape of the rings can tell a lot about the conditions in which that tree was growing. That is why dendrochronology is such a useful tool. By looking at tree rings from all over the world, researchers can tell what was going on at that point in time. And, though it was long thought that this was a phenomenon restricted to seasonal forests, we are finding that even some tropical trees produce annual growth rings. This is especially true in regions that have a measurable dry season. It just goes to show you that data comes in many shapes, sizes, and forms.
LEARN MORE ABOUT DENDROCHRONOLOGY IN EPISODE 247 OF THE IN DEFENSE OF PLANTS PODCAST
Further Reading: [1] [2] [3]
Bark!
Photos by SNappa2006 (CC BY 2.0), nutmeg66 (CC BY-NC-ND 2.0), Eli Sagor (CC BY-NC 2.0), and Randy McRoberts (CC BY 2.0)
Say "tree bark" and everyone knows what you're talking about. We learn at an early age that bark is something trees have. But what is bark? What is its purpose and why are there so many different kinds? Indeed, there would seem to be as many different types of bark as there are trees. It can even be used as a diagnostic feature, allowing tree enthusiasts to tease apart what kind of tree they are looking at. Bark is not only fascinating, it serves a serious adaptive purpose as well. To begin to understand bark, we must first look at how it is formed.
To start out, bark isn't a very technical term. Bark isn't even a single type of tissue. Instead, bark encompasses several different kinds of tissues. If you remember back to Plant Growth 101, you may have heard the word "cambium" get thrown around. Cambium is a layer of actively dividing tissue sandwiched between the xylem and the phloem in the stems and roots of plants. As this layer grows and divides, the inside cells become the xylem whereas the outside cells become the phloem.
Successive divisions produce what is known as secondary phloem. This is where the bark begins. On the outside of this secondary phloem are three rings of tissues collectively referred to as the "periderm." It is the periderm which is responsible for the distinctive bark patterns we see. As a layer of cells called the "cork cambium" divides, the outer layer becomes cork. These cells die as soon as they are fully developed. This layer is most obvious in smooth bark species such as beech.
Similar to insect growth, however, the growth of the insides of a tree will eventually outpace the bark. When this happens, the periderm begins to split and cracks will begin to appear in the bark. This phenomenon is most readily visible in trees like red oaks. When this starts to happen, cells within the secondary phloem begin to divide. This forms a new periderm underneath the old one. The cumulative result of this results in alternating layers of old periderm tissue referred to as "rhytidome."
This gives trees like black cherry their scaly appearance or, if the rhytidome consists of tight layers, the characteristic ridges of white ash and white oak. Essentially, the distribution and growth pattern of the periderm gives the tree its bark characteristics. But why do trees do this? Why is bark there in the first place?
The dominant role of bark is protection. Without it, vital vascular tissues risk being damaged and the tree would rapidly loose water. It also protects the tree from pests and pathogens. The cell walls of cork contain high amounts of suberin, a waxy substance that protects against desiccation, insect attack, as well as fungal and bacterial infection. Thick bark can also insulate trees from fire.
Countless aspects of the environment have influenced the evolution of tree bark. In some species such as aspen or sycamore, the trunk and stems function as additional photosynthetic organs. In these species, cork layers are thin and often flaky. Shedding these thin layers of bark ensures that buildup of mosses, lichens, and other epiphytes doesn't interfere with photosynthesis. The white substance on paper birch bark not only inhibits fungal growth, it also helps prevent desiccation while at the same time making it distasteful for browsing insects and mammals alike.
When you consider all the different roles that bark can play, it is no wonder then that there are so many different kinds. This is only the tip of the ice berg. Entire scientific careers have been devoted to understanding this group of tissues. For now, winter is an excellent time to start noticing bark. Take some time and get to know the trees around you for their bark rather than their leaves.
Photo Credits: Eli Sagor (bit.ly/1OTnA8H), Randy McRoberts (bit.ly/1PgzH35), Lotus Johnson (bit.ly/1JyVt1E), SNappa2006 (bit.ly/1TkjHil), and nutmeg66 (bit.ly/1QwyZQ8)
Further Reading:
http://www.botgard.ucla.edu/
html/botanytextbooks/generalbotany
/barkfeatures/typesofbark.html
http://dendro.cnre.vt.edu/forestbiolog
y/cambium2_no_scene_1.swf
http://life9e.sinauer.com/life9e/pages
/34/342001.html
http://www.botgard.ucla.edu/html/bo
Tiger's Jaw
Photo by Mike Keeling licensed under CC BY-ND 2.0
Behold the ominous beauty of the genus Faucaria. These succulent herbs in the family Aizoaceae are native to South Africa and are known commonly as tiger's jaws. The first time I encountered one of these plants, I was a little hesitant to get too close. Despite their appearance, however, they are rather tame. What looks like a sturdy defense actually has more to do with water.
Faucaria are denizens of the dry. Their stubby, succulent leaves act as water storage devices that allow the plant to go some time without water. As new leaves are produced, they emerge in pairs with their serrated edges interlocking like teeth. Once mature, the edges separate and the pair of leaves open up like a carnivorous maw.
The "teeth" of these "jaws" are a unique adaptation for acquiring extra water. Because it rains infrequently, the plant does its best to take advantage of moisture in the air. The teeth act as condensation points, mopping up dew and fog and directing it towards the roots. In this way, Fucaria are able to maintain themselves even in the absence of rain.
Photo by Mike Keeling licensed under CC BY-ND 2.0
And maintain themselves they do! Like many other members of the family, Faucaria produce unexpectedly large flowers for their size. The blooms erupt from the middle of each pair of leaves, almost as if they were being regurgitated. Seeing a mature population in full bloom is an experience you won't soon forget.
Photo Credit: [1] [2] [3]
Further Reading: [1]
Conifer Leaf Drop
It's that time of year when evergreen trees become apparent. The most obvious are the conifers. These trees hold steady while everything else seems to be in a mad rush for winter. Despite the term "evergreen" the conifers are nonetheless preparing for winter as well, though on a much more subtle level. Anyone paying close attention will see some color changes happening to them too. Despite the designation as "evergreen" conifers do shed leaves.
Timescales are everything for us humans. We tend to notice things that happen relatively fast, like an entire forest turning color in only a few weeks. The conifers have adopted a strategy that isn't as in tune with our perception. Conifers, for the most part, specialize in harsh habitats. Excelling in poor soils and extreme cold, they tend to invest in the long term. Needles are one such adaptation. Their minimal surface area and structural integrity make up for their costly production in nutrient poor conditions. When a conifer produces needles, they need to last for a while.
And that is exactly what they do. The average conifer needle has a lifetime of roughly 2 years (with some exceptions of course). It doesn't make sense for them to bank on a whole new set leaves every year. Because of the way they grow, conifers usually shed their leaves from the inside out. New leaves are produced at the tips of branches and, as older leaves get shaded out, conifers cut their losses and drop them. If you take a close look at conifers during the fall, this pattern becomes readily apparent.
Leaf drop doesn't always happen quickly either. They are often spaced out over time. One of the reasons I like plants so much is that they operate on vastly different timescales than we do. As you become more and more familiar with different species, plants can teach you to start looking at things a bit different than you are used to. Get outside and find some needle dropping conifers of your own.
Further Reading: [1]
The Darth Vader Begonia
Cue the Imperial March, it is time to talk about the Darth Vader Begonia. This atramentous plant had only been known to the world since 2014. The discovery of this species (as well as two other new Begonia species) occured in Sarawak, on the island of Borneo. This region is a hot spot for plant diversity and this is especially true for begonias. A combination of diverse terrain and varied microclimates have led to an explosion of speciation events resulting in endemic species found nowhere else in the world.
With its leaves so deeply green that they almost appear black and deep red flowers it's not a stretch to imagine why this begonia has been named Begonia darthvaderiana. Until 2014, no one had ever laid eyes on this species, not even the locals. It was found growing in the deep shade of a forested cliff mixed in among other shade-loving vegetation. It is likely that the dark coloration of its leaves enables it to take advantage of what little sunlight makes it down to the forest floor.
Not long after its discovery was reported, something alarming happened. The so-called Darth Vader begonia began appearing for sale online. With a price tag of $80+, this is one expensive little plant. Apparently a plant poacher from Taiwan managed to smuggle some plants out of the country. This is especially upsetting because of its extreme rarity. Despite its namesake, the force is not strong enough to protect this species from greedy collectors. If you have somehow managed to obtain one of these plants, please do everything in your power to propagate it. Plants produced in captivity take pressure off of wild populations.
This was not the only new begonia species to be named after a Star Wars character. A larger species with green and silver leaves was given the scientific name of Begonia amidalae after Queen Amidala. It too is endemic to the region. The future of these plants as well as many others hangs in the balance. A growing human population is putting pressure on the rainforests of Borneo. As more and more forest is lost to development, countless endemic species are disappearing with it. This is yet another example of why land conservation is a must. Please consider lending your support to organizations such as the Rainforest Trust. Together, we can ensure that there are wild spaces left.
CLICK HERE TO HELP LAND CONSERVATION EFFORTS IN BORNEO
Photo Credit: Che-Wei Lin, Shih-Wen Chung, & Ching-I Peng
Further Reading: [1] [2]
Is it a pine? Is it an apple? It's neither!
Photo by Fractalux Public Domain
Pineapples - the fruit that is neither a pine nor an apple. In reality, pineapples are a type of bromeliad. The genus to which they belong, Ananas, is comprised of something like 7 different species, all of which are native to Central and South America. Considering we rarely encounter these plants outside of a grocery store, it is no wonder then that many are surprised to realize how pineapples grow.
Photo by H. Zell licensed under CC BY-SA 3.0
The fruit itself is not the entire plant. It is made up of many fruits that fuse together after flowering. The flowers themselves are quite lovely and originate from the center of the hexagonal units that make up the tough rind. The whole inflorescence arises from the center of a large rosette of leaves. Only when you see the entire plant does the bromeliad affinity become apparent. Like all other bromeliads, pineapples undergo vegetative reproduction as well. Small offshoots called "pups" arise from the base of the plant and the axils of the leaves. These can take root and grow into clones of the parent plant.
In the wild, pineapples require pollination to set seed. This is undesirable in cultivation because pollination means lots of seeds that consumers don't want to contend with. Because of this, pineapples are gassed with ethylene, the simplest of plant hormones. Ethylene causes the fruits to artificially ripen without being pollinated. In this way, no ovules mature into seeds.
Photo by hiroo yamagata licensed under CC BY-SA 2.0
The dirty little secret about pineapple farming is that it is done at great environmental cost. The dominant producer of pineapples is Costa Rica. Because of the humid, tropical climate, insects and fungi flourish. In order to ensure that production is maximized, pineapple farmers dump thousands of gallons of pesticides and herbicides onto their crops. These farms are largely void of all other lifeforms save for endless hectares of pineapples. This, however, is not a story unique to pineapple farming. The same could be said for all other forms of monoculture farming.
Photo Credits: Fractalux, H. Zell, and hiyori13 - Wikimedia Commons
Further Reading:
http://www.kew.org/science-conservation/plants-fungi/ananas-comosus-pineapple
http://www.theguardian.com/business/2010/oct/02/truth-about-pineapple-production
The Strangest Spiderworts
What if I told you that what you are looking at right now is a member of the spiderwort family (Commelinaceae)? At first, I didn't believe it either. Even after seeing those magnificent blooms, it took a bit of convincing. Regardless, the genus Cochliostema represents some of the strangest members of the family.
Cochliostema can be found growing in Central and South America. There are only two species in the genus, C. odoratissimum and C. jacobianum. My introduction to this group was Cochliostema odoratissimum. It is one of those plants that you smell before you see. The fragrance of the flowers is something worth experiencing. Because I lack the descriptive vocabulary needed to convey the proper respect, I'm going to ask you to trust me when I say that its lovely. The fragrance emanates from some seriously awesome flowers. It has been suggested that they are quite possibly the most complex flowers in the entire family. They are born on a type of spike called a "thyrse." Each flower consists of 3 sepals, 3 fringed petals, 3 stamens, which are fused in the upper half of the flower, and 3 carpels fused into a single pistil. The end result, as you can clearly see, is stunning.
The plants themselves are epiphytes, though they will grow terrestrially if they happen to fall from their host tree. As evidenced by their radial growth habit, they are akin to bromeliads in their ecology with at least one species considered a tank epiphyte. As such, they provide ample habitat in the canopy for a variety of flora and fauna.
Further Reading:
http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.2000.tb02348.x/abstract
Pumpkins!
Ah, the pumpkin. Nothing signifies fall to me more than this lovely orange gourd. Who doesn't love the eerie glow of a jack-o-lantern or the pleasing taste of roasted pumpkin seeds? Don't even get me started on my love for pumpkin pie! This gourd has certainly ingrained itself in our culture but, from a botanical standpoint, pumpkins, or at least the species from which they hail, are quite interesting.
Cucurbita pepo is native to North America and is a member of the gourd family. Though it should come as no surprised, this group is characterized by the large fruits that they produce. The gourds themselves are actually a type of berry. C. pepo is one of the oldest species of plants ever domesticated. Records from Mexico show humans cultivating this species as far back as 8750 BC. The origins of this domesticated species are still a bit fuzzy but experts believe that C. pepo is a hybrid of Cucurbita texana and Cucurbita fraterna, though the former may just be a feral form of C. pepo.
As it turns out, pumpkins are only one domesticated variety of Cucurbita pepo. Many of the gourds we enjoy are also varieties of this species. These include crops like acorn squash, delicata squash, gem squash, several types of ornamental squash (often called "gourds"), pattypan squash, spaghetti squash, yellow crookneck squash, yellow summer squash, and zucchini. Pretty impressive, no?
Many of these varieties are believed to have originated in the southern portions of Mexico but that is still being resolved. So, if you find yourself carving pumpkins and eating some other form of gourd, like spaghetti squash, realize that you are spending your evening celebrating the many uses of a single species!
Photo Credit: Thom Pirson & Wikimedia Commons
Further Reading: [1] [2] [3] [4] [5]
Bird's Foot Violet
As a life long denizen of deciduous forests, prairies and savannas present an entirely new set of stimuli. A recent excursion into an expansive oak savanna found me overwhelmed by the beauty of such places. Being mid October, the color pallet of the landscape ranged from myriad shades of reds, browns, yellows, and oranges. I was walking through a particularly sandy patch of soil when something caught my eye. A little flash of lavender shone through the amber grasses. To my astonishment I had found a plant that has managed to elude me for many years.
What I had found was a bird's-foot violet (Viola pedata). Its deeply divided leaves, which faintly resemble a bird's foot, are unmistakable. What was even more fantastic was that this particular plant was in full bloom. I looked around and found only a small handful of other plants. This one was the only one in bloom. Though not unheard of for this time of year, I couldn't help but revel in the serendipity of the moment.
Like all members of the genus Viola, bird's-foot violet is a photoperiodic plant. By this I mean that all aspects of its growth are sensitive to the relative amount of sunlight in any given day. Violets are generally spring time plants, however, the shortening days and cooler temperatures of fall aren't that different from spring. As such, this lovely little plant was perhaps a bit confused by the cool October weather. I didn't see any pollinators out and about but that doesn't mean that a hardy bumblebee wouldn't be lucky to stumble into its blooms.
Back in my home state of New York, this particular species of violet is truly a rare find. The kind of habitats which it frequents have been largely destroyed. It is a xeric species that doesn't appreciate water hanging around for very long. Finding it growing in mostly sand was not surprising to say the least. Like most other violets, its seeds come complete with their own fleshy protuberance called an elaiosome. The purpose of these fatty attachments are to attract foraging ants in the genus Aphenogaster. The ants find the elaiosomes to their liking and take them back to their nest. Once the elaiosome is eaten, the seed is discarded into a refuse chamber inside the nest. There it finds a favorable microsite for germination full of nutrient-rich ant compost.
Further Reading:
http://www.jstor.org/stable/3668940?seq=1#page_scan_tab_contents
http://www.illinoiswildflowers.info/prairie/plantx/bird_violet.htm
Green Islands
Autumn is here and all across the northern hemisphere deciduous trees are putting on a show unlike anything else in the natural world. The range of colors are spectacular both from afar and up close. If you're like me then every single leaf is worth investigation. The trees are shedding their leaves in preparation for dormancy. The leaves aren't dying outright. Instead, the trees are reabsorbing the chemicals involved in photosynthesis as a way of getting back some of the energy investment that went in to producing them in the first place.
If you look closely at some leaves, however, you may notice green spots in an otherwise senescent leaf. Why is it that certain parts of these leaves are still photosynthetically active despite the rest of the photosynthetic machinery shutting down around them? The answer to this question is way cooler than I ever expected.
These "green islands" as they are called are almost always associated with an insect. If you look closely towards the base of these spots you will usually find a tiny leaf mining larvae of a moth busy munching away at the remaining photosynthetic tissue. The most obvious conclusion at this point would be to say that the moth larvae are the cause of the green islands. However, it is not that simple.
When researchers raised the moth larvae under sterile conditions, they did not produce the green island effect. This proved to be a bit of a conundrum. Why would this happen in the wild but not under sterile conditions in a lab? The answer is bacteria.
It would appear that the moth larvae have a symbiotic relationship with bacteria living on their bodies. These bacteria interact with the tissues of the leaf and alter the production of cytokinins. In the leaf, cytokinins inhibit leaf senescence. When the plant switches into dormancy mode, cytokinin production is shut down. The bacteria, however, actually ramp up cytokinin production throughout the tissues surrounding the larva. The result of which is a small region or "island" of tissue with prolonged photosynthetic life.
Because of this, the larvae are able to go on feeding well into the fall when food would otherwise become nonexistent. By harboring these bacteria, the moths are able to get more out of each seasons reproductive efforts instead of simply stopping once fall hits. This is the first ever evidence of insect bacterial endosymbionts have been shown to manipulate plant physiology, though it most certainly will not be the last.
I would like to thank Charley Eiseman for the use of this photo as well as inspiring this post. Charley is the man behind one of my all time favorite blogs Bug Tracks so make sure to visit and like Northern Naturalists.
Further Reading: [1] [2] [3] [4] [5]
Itty Bitty Bartonia
Every plant enthusiast has a handful of species that they search high and low for any time they find themselves out and about. It may be a species you have seen a bunch of times or one your have only read about in the literature. Either way, the search image burns strong in your mind so that when you finally come across the species in question, it is like seeing a celebrity. For me, one of those species is Bartonia virginica.
It may not look like much. Indeed, it is a rather diminutive plant, barely poking its flowers out of the shadows cast by pretty much every other plant near by. However, when conditions are just right, this little gentian seems to flourish. With leaves that have been reduced to small scales that sheath the dainty stem in a couple places, all that really stands out are the tiny, cream colored flowers that cluster near the top. A close inspection of the flowers with a hand lens reveals the unmistakable morphology that runs true throughout the gentian family.
Whereas the stem of the plant does contain chlorophyll, it has long been suspected that this plant must rely on other means of obtaining carbon due to its highly reduced leaves. A paper published in 2009 by Cameron et al., was able to shed some light on this matter. As it turns out, there is strong evidence in support of B. virginica being partially mycoheterotrophic.
This is such a cool little gentian. I was so happy to have come across some. Sometimes it's not always the biggest or the showiest that make our day, but rather the subtle and unique.
Further Reading:
http://plants.usda.gov/core/profile?symbol=bavi3
http://www.amjbot.org/content/97/8/1272.short
Pearly Everlasting
Photo by Pendragon39 licensed under Public Domain
I have gardened with a lot of native plants over the years but pearly everlasting (Anaphalis margaritacea) may be one of my favorites. Not only is it easy to grow, this tough little plant can handle some pretty harsh soil conditions. In the wild, I often find it growing along gravelly roadsides where it puts on quite a show. Let's be honest with each other, who doesn't love a fuzzy plant.
Pearly everlasting is a member of the largest dicot family on the planet, the asters. As such, what appears to be single flowers doing their best imitation of a sunny side up egg is actually a collection of many tiny flowers clustered together to look like one big one. In a sense, this is a form of floral mimicry.
What is most unique about pearly everlasting is that it is dioecious. Individual plants produce disks that are either male or female. I can't really think of other asters that adopt this strategy. And what an awesome strategy it is. Being dioecious means cross-pollination. The reproductive disk flowers are those yellow ones in the center. The pearly white outer ring of each inflorescence is actually made up of a dense cluster of involucre.
© 2009 Walter Siegmund licensed under GNU Free Documentation License, Version 1.2
Did I mention this plant is fuzzy? Dense trichomes cover the stem and underside of each leaf. Hairs like this are adaptations to reduce water loss and overheating. However, there is evidence that in pearly everlasting, these hairs can also reduce feeding by spittlebugs. Nymphs looking for a tasty plant to drill into cannot seem to penetrate the dense growth of trichomes, which means each pearly everlasting gets to hold on to its sap.
Again, I can't speak highly enough about this species. It is native to much of North America and, in this writers opinion, should be in the drier portions of every native garden. All you need are a handful of seeds and a small population of pearly everlasting will soon be keeping you company.
Photo Credit: Wikimedia Commons
CAM Photosynthesis
I was in a lecture the other day and I heard something that made the plant nut inside of me chuckle. The professor was trying to make the point that C3 photosynthesis is the most common photosynthetic pathway on the planet. To do this he said "it is the vanilla pathway." In this context, he was using vanilla as an adjective meaning "plain or ordinary." Of course, this was all very facetious, however, I thought it interesting and funny how, if taken literally, that statement was just plain wrong.
I have written before about the reproductive ecology of Vanilla orchids (http://bit.ly/1LcC857). They are anything but vanilla the adjective. The other part of the statement that was wrong (again, if taken literally) is that C3 is the photosynthetic pathway of the vanilla orchid. In reality, vanillas are CAM photosynthesizers.
Last week I wrote about the C4 pathway and how it has helped plants in hot, dry places, but the CAM pathway is yet another adaptation to such climates. The interesting thing about CAM photosynthesis is that it separates out the different reactions in the photosynthetic pathway on a temporal basis.
CAM is short for Crassulacean acid metabolism. It was first described in succulents in the family Crassulaceae. Hence the name. Similar to the C4 pathway, CO2 is taken into the leaves of the plant and stored as an organic acid. This is where the process differs. For starters, having acid hanging around inside your leaves is not necessarily a good thing. CAM plants deal with this by storing it in large vacuoles. That is one reason for the succulent appearance of many CAM species.
Because these plants so often grow in hot, dry climates, they need to minimize water loss. Water evaporates from holes in the leaves called stomata so to avoid this, these holes must be closed. However, closing the stomata means not letting in any CO2 either. Whereas C4 plants get around this by only opening their stomata during the cooler hours of the day, CAM plants forgo opening their stomata entirely when the sun is up.
Instead, CAM plants open their stomata at night when the vapor pressure is minimal. This ensures that water loss is also minimal. Like camels storing water for lean times, CAM plants store CO2 as organic acid to use when the sun rises the next day. In this way, CAM plants can close their stomata all the while the hot sun is baking the surrounding landscape yet still undergo ample photosynthesis for survival.
Not all orchids do this. In fact, some can switch photosynthetic pathways in different tissues. However, there are many other CAM plants out there including some very familiar species like pineapples, cycads, peperomias, and cacti. If you're like me and prone to talking to your plants, it is probably best to talk to your CAM plants after the sun has set. Not only does it confuse neighbors and friends, it provides them with CO2 when they are actively absorbing it.
Further Viewing: https://www.khanacademy.org/science/biology/cellular-molecular-biology/photosynthesis/v/cam-plants
What a Dichaea
The orchid genus Dichaea includes some of the strangest orchids i have ever seen in person. Take this one for example. My sources tell me this is likely D. globosa. Right off the bat, the bristly seed pods are a tell for this genus. With this particular species, each stem juts off of the trunk of a tree at a near 90 degree angle. The stem itself is horizontally flattened and the subtle yet beautiful flowers emerge from between the leaves and are presented below the plant, facing the ground. I had seen this orchid out of flower in a few places in Costa Rica, however, I was lucky enough to stumble across these individuals in flower while hiking in Panama. An exciting find for this orchid fanatic!