Everlasting or Seven Years Little

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Common names are a funny thing. Depending on the region, the use, and the culture, one plant can take on many names. In other situations, many different plants can take on a single name. Though it isn't always obvious to those unfamiliar with them, the use of scientific names alleviates these issues by standardizing the naming of things so that anyone, regardless of where they are, knows what they are referring to. That being said, sometimes common names can be entertaining.

Take for instance, plants in the genus Syncarpha. These stunning members of the family Asteraceae are endemic to the fynbos region of the Eastern and Western Cape of South Africa. In appearance they are impossible to miss. In growth habit they have been described as "woody shrublets," forming dense clusters of woody stems covered in a coat of woolly hairs. Sitting atop their meter-high stems are the flower heads.

Each flower head consists of rings of colorful paper-like bracts surrounding a dense cluster of disk flowers. The flowering period of the various species can last for weeks and spans from October, well into January. Numerous beetles can be observed visiting the flowers and often times mating as they feed on pollen. Some of the beetles can be hard to spot as they camouflage quite well atop the central disk. Some authors feel that such beetles are the main pollinators for many species within this genus.

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Their mesmerizing floral displays are where their English common name of "everlasting" comes from. Due to the fact that they maintain their shape and color for quite a long time after being cut and dried, various Syncarpha species have been used quite a bit in the cut flower industry. A name that suggests everlasting longevity stands in stark contrast to their other common name. 

These plants are referred to as "sewejaartjie" in Afrikaans, which roughly translates to "seven years little." Why would these plants be referred to as everlasting by some and relatively ephemeral by others? It turns out, sewejaartjie is a name that has more to do with their ecology than it does their use in the floral industry.

As a whole, the 29 described species of Syncarpha are considered fire ephemerals. The fynbos is known for its fire regime and the plants that call this region home have evolved in response to this fact. Syncarpha are no exception. They flower regularly and produce copious amounts of seed but rarely live for more than 7 years after germination. Also, they do not compete well with any vegetation that is capable of shading them out.

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Instead, Syncarpha invest heavily in seed banking. Seeds can lie dormant in the soil for many years until fires clear the landscape of competing vegetation and release valuable nutrients into the soil. Only then will the seeds germinate. As such, the mature plants don't bother trying to survive intense ground fires. They burn up along with their neighbors, leaving copious amounts of seeds to usher in the next generation.

Research has shown that its not the heat so much as the smoke that breaks seed dormancy in these plants. In fact, numerous experiments using liquid smoke have demonstrated that the seeds are likely triggered by some bio-active chemical within the smoke itself.

So, there you have it. Roughly 29 plants with two common names, each referring back to an interesting aspect of the biology of these plants. Despite their familiarity and relative ease of committing to memory, the common names of various species only get us so far. That's not to say we should abolish the use of common names altogether. Learning about any plant should be an all encompassing endeavor provided know which plant you are referring to.

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

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

 

Red or White?

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Who doesn't love a nice oak tree? One cannot overstate their importance both ecologically and culturally. Although picking an oak tree out of a lineup is something many of us are capable of doing, identifying oaks to species can be a bit more challenging. This is further complicated by the fact that oaks often hybridize. Still, it is likely you have come across some useful tips and tricks for narrowing down your oak choices. One such trick is distinguishing between the red oaks and the white oaks. If you're anything like me, this is something you took for granted for a while. Is there anything biologically or ecologically meaningful to such a split?

In short, yes. However, a true appreciation of these groups requires a deeper look. To start with, oaks are members of the genus Quercus, which belongs in the family Fagaceae. Globally there are approximately 400 species of oak and each falls into one of three categories - the red oaks (section Lobatae), the white oaks (section Quercus), and the so-called "intermediate" oaks (section Protoblanus). For the sake of this article, I will only be focusing on the red and white groups as that is where most of the oak species reside. The intermediate oak group is made up of 5 species, all of which are native to the southwestern United States and northwestern Mexico.

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As is common with oak identification, reliable techniques for distinguishing between the two groups can be tricky. Probably the most reliable feature is located on the inner surface of the acorn cap. In white oaks, it is hairless or nearly so, whereas in red oaks, it is covered in tiny hairs. Another useful acorn feature is the length of time it takes them to germinate. White oak acorns mature in one season and germinate in the fall. As such, they contain lower levels of tannins. Red oak acorns (as well as those of the intermediate group) generally take at least two seasons to mature and therefore germinate the following spring. Because of this, red oak acorns have a much higher tannin content. For more information on why this is the case, read this article.

Tyloses in white oak xylem.

Less apparent than acorns is the difference in the wood of red and white oaks. The wood of white oaks contains tiny structures in their xylem tissues called tyloses. These are absent from the wood of red oaks. The function of tyloses are quite interesting. During extreme drought or in the case of some sort of infection, they cut off regions of the xylem to stop the spread of an embolism or whatever may be infecting the tree. As such, white oaks tend to be more rot and drought resistant. Fun fact, tyloses are the main reason why white oak is used for making wine and bourbon barrels as it keeps them from leaking their contents.

More apparent to the casual observer, however, is leaf shape. In general, the white oaks produce leaves that have rounded lobes, whereas the red oaks generally exhibit pointed lobes with a tiny bristle on their tips. At this point you may be asking where an unlobed species like shingle oak (Quercus imbricaria) fits in. Look at the tip of its leaf and you will see a small bristle, which means its a member of the red oak group. Similarly, the buds of these two groups often differ in their overall shape. White oak buds tend to be smaller and often have blunted tips whereas the buds of red oaks are generally larger and often pointed.

Tricky leaves of the shingle oak (Quercus imbricaria). Note the bristle tip!

Tricky leaves of the shingle oak (Quercus imbricaria). Note the bristle tip!

Despite this broad generalizations, exceptions abound. This is further complicated by the fact that many species will readily hybridize. Quercus is, after all, a massive genus. Regardless, oaks are wonderful species chock full of ecological and cultural value. Still, oak appreciation is something we all need more of in our lives. I encourage you to try some oak identification of your own. Get outside and see if you can use any of these tricks to help you identify some of the oaks in your neighborhood.

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

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

Meet The Powder Gun Moss

I get very excited when I am able to identify a new moss. This is mainly due to the fact that moss ID is one of my weakest points. I was sitting down on a rock the other day taking a break from vegetation surveys when I looked to my right and saw something peculiar. The area was pretty sloped and there was some exposed soil in the vicinity. Covering some of that soil was what looked like green fuzz. Embedded in that fuzz were these strange green urns.

I busted out my hand lens and got a closer look. This was definitely a moss but one I had never seen before. The urns turned out to be capsules. Later, a bit of searching revealed this to be a species of moss in the genus Diphyscium. This genus is the largest within the family Diphysciaceae and here in North America, we have two representatives - D. foliosum and D. mucronifolium.

These peculiar mosses have earned themselves the common name 'powder gun moss.' The reason for this lies in those strange sessile capsules. Unlike other mosses that send their capsules up on long, hair-like seta in order to disperse their spores on the faintest of breezes, the Diphyscium capsules remain close to the ground. In lieu of wind, a powder gun moss uses rain. In much the same way puffball mushrooms harness the pounding of raindrops, so too do the capsules of the powder gun moss. Each raindrop that hits a capsule releases a cloud of spores that are ejected into an already humid environment full of germination potential.

Luckily for moss lovers like myself, the two species of Diphyscium here in North America tend to enjoy very different habitats. This makes a positive ID much more likely. D. foliosum prefers to grow on bare soils whereas D. mucronifolium prefers humid rock surfaces. Because of this distinction, I am quite certain the species I encountered is D. foliosum. And what a pleasant encounter it was. Like I said, it isn't often I accurately ID a moss so this genus now holds a special place in my mind.

Further Reading: [1] [2]

 

The Fuzziest of Flowers

Describing plants can be quite a task for taxonomists. When a new species is discovered, the honor of naming it often goes to the discoverer. At the very least, they have some input. Some folks go for the more traditional rout and give the plant a descriptive name rooted in either Latin or Greek. Others decide to name the plant in honor of a botanist of the past or perhaps a loved one. Still others take a stranger approach in order to immortalize a famous celebrity. However, in doing so they risk taking something away from the species in question.

Instead of a descriptive name that clues you in on specific features of the plant, instead you hit an etymological dead end in which you are stuck with nothing more than a last name. This became quite apparent to University of Alabama botanist John Clark when it was time to name a newly discovered plant species from South America. 

Had things been slightly different, the recently discovered Kohleria hypertrichosa would have been named after Chewbacca. One look at the flowers of this species and you can understand why. The long tubular petals of this gesneriad are covered in dense, fuzzy hair. This is unlike any other plant known to science. The appearance of these odd fuzz balls may seem puzzling at first but considering where this plant was found growing, it quickly becomes apparent that these flowers are a marvelous adaptation in response to climate. 

Kohleria hypertrichosa is only known to grow in a very narrow swath of mountainous cloud forest in the Ecuadorian Andes. At home between elevations of 3,600 and 6,600 feet above sea level, this wonderful gesneriad experiences some pretty low temperatures for a tropical region. It is likely that the thick layer of hairs keeps the flowers a bit warmer than the surrounding air, offering a welcoming microclimate for pollinators. This could potentially make them much more likely to be pollinated in a habitat where pollinators may be in short supply. 

At the end of the day, Clark decided to stick with a more traditional name for this new species. Its scientific name is no less interesting as a result. The specific epithet 'hypertrichosa' is derived from a condition in humans known as hypertrichosis, or werewolf syndrome, in which a person grows excessive amounts of body hair. 

Photo Credit: Andreas Kay [1]

Further Reading: [1]

How North America Lost Its Asters

It's that time of year in northern North America where many of the most famous and easily recognized species come into flower, the asters. Some of my favorite plants once resided in this genus, but did you know that referring to our North American representatives as "asters" is no longer taxonomically accurate?

Since the time of Linnaeus, plants and animals have been categorized based on morphological similarities. With recent advances made in the understanding and sequencing of DNA, a new and more refined method of classifying the relationships of living organisms has been added to the mix. Much of what has been taken for granted for the last few decades is being changed. One group that has been drastically overhauled are the North American asters. At one time there were roughly 180 species of North American flowering plants that found themselves in the genus Aster. Today, there is only one, Aster alpinus, which enjoys a circumboreal distribution. 

Because the concept of "Aster" was developed using an Old World species (Aster amellus), New World asters were not granted that distinction. The New World species have shown to have their own unique evolutionary history and thus new genera were either assigned or created. By far, the largest New World genus that came out of this revisions is Symphyotrichum. This houses many of our most familiar species including the New England aster (Symphyotrichum novae-angliae). Some of the other genera that absorbed New World aster include Baccharis, Archibaccharis, Ericameria, Solidago, and Machaeranthera, just to name a few.

Taxonomy is often a difficult concept to wrap your head around. It is constantly changing as we come up with better ways of defining organisms. Even the concept of a species is something biologists have a hard time agreeing on. Surely, genetic analyses offer some of the best methods we have to date, a fact that the Angiosperm Phylogeny Group is constantly refining.

For some, this is all a bunch of silly name changes but for others this is the most important and dynamic form of natural science on the planet. Having a standard for naming organisms is a crucial component of understanding biodiversity. With a name, you can take the next step in getting to know and understand a beloved species. One thing to consider is that, as species are split and regrouped, often times what was thought to be one species turns out to be many. In the case of organisms which are threatened or endangered, a split like that can unveil a disastrous elevation into a far more dismal ranking.

Further Reading: [1] [2]