Vulnerable Vegetation, or Plants in Peril

Finding a rare plant in the wild, no matter how otherwise unremarkable it may be, is always an awe-inspiring experience.  Perhaps the only thing more awe-inspiring for a botanist is a close encounter with a rare and endangered plant.  Such species occupy much of our attention, and rightly so, for these are the species most in need of study and protection.  Endangered species, according to the Endangered Species Act of 1973 (ESA), are species (including named taxonomic subspecies and varieties) threatened with extinction throughout all or most of their range.  While you probably know that endangered species are protected under federal law, you may not really know what that means.  In a previous post (see March 2017), I wrote about seeing an endangered member of the myrtle family from Puerto Rico, Myrcia paganii.  Having recently had the privilege of observing two endangered species of Eugenia in the wild, I became interested in knowing how the endangered species act works for plants.

But first, the plants.  Currently there are a total of four federally endangered species of Eugenia, two in Puerto Rico, one in Hawaii, and one on Guam.  I saw the Puerto Rican ones, both of which are only found on this island.  The first one I saw was Eugenia woodburyana.  This species was described in 1980.  It is restricted to dry forest areas in southwestern Puerto Rico.  Never having seen a live plant of this species before, I was impressed by the size of its peculiar, 8-winged fruits, the fuzzy leaves, and the attractive multi-stemmed growth habit of mature trees.

Eugenia woodburyana: habit

Eugenia woodburyana: foliage

Eugenia woodburyana: ripening fruit

Later, I encountered Eugenia haematocarpa in the Sierra de Cayey.  This species was described in 1963.  It can be found on steep slopes in wet mountain forests.  I was particularly keen to see this species, which has rarely been collected, has unusually large leaves, and bears flowers and fruits directly from its trunk!  Though flowers can be elusive, I was fortunate to come upon several flowering individuals.

Eugenia haematocarpa: flowers

Eugenia haematocarpa: foliage

So how are these species protected?[1]  The ESA prohibits buying, selling, or transporting endangered species between states or internationally, as interstate and foreign commerce are regulated by the federal government.  Endangered species are also protected on federal land and cannot be harmed or collected.  Exceptions for scientific research and propagation are allowed by permit.  On private land, the rules vary.  Endangered animals are protected wherever they are found, but plants do not receive federal protection on private land unless a federal agency is somehow involved there.  Any additional protection on private land is left up to the states, which usually do not have very restrictive laws.  It’s fair to say that the law of the land is zoocentric.

The U.S. Fish and Wildlife Service (FWS) is the main federal agency responsible for implementing the ESA, but all federal agencies bear responsibility for the protection of endangered species as they carry out their activities.  FWS determines which species are endangered based on the best available data.  FWS is also responsible for designating the “critical habitat” that a species requires for survival, developing a conservation plan, and reporting periodically on the progress made in conserving each endangered species.[2]  For Eugenia woodburyana, the latest report recommends downgrading the species to threatened due in part to recently discovered populations.  Though that might make it just another rare species, I, for one, prefer it that way.

[1] The information provided here is summarized from the following website:  https://www.fs.fed.us/wildflowers/Rare_Plants/conservation/lawsandregulations.shtml

[2] Basic information and documents on each endangered species can be found here:  https://www.fws.gov/endangered/

The Species Question

My mind raced as I stood before the audience trying to figure out how best to approach answering the question.  After delivering a brief talk about my research, I was asked, innocently enough, how I knew when a plant was different enough to be considered a different species.  I took the easy way out.  The question was asked in the context of DNA evidence, so I replied that I use physical characteristics to decide these matters.  Though this got me off the hook, the underlying question remained unanswered; I merely shifted the question from the level of molecules to morphology.

How to define the boundaries between species, the “species problem,” has no generally agreed upon answer—hence my hesitation.  Traditionally, species were a matter of expert opinion, but such a practice is unjustifiable for a scientific discipline.  A variety of species concepts now vie for acceptance in the extensive literature on the subject, including the view that no one concept is appropriate for all organisms or purposes.  How could such a fundamental concept still be up for debate?  Divergent concepts reflect a diversity of views on both biological diversity itself and the way we study it.  The following cheat sheet briefly describes some of the main answers to the species problem:

1. Phenetic – When all of their properties are considered, species have a certain amount of quantifiable difference between them.
2. Biological – Species are separated from one another by the inability (not just lack of opportunity) to interbreed in nature.

Portlandia grandiflora

Portlandia proctorii

A pink-flowered hybrid between Portlandia grandiflora and the red-flowered species P. coccinea. These hybrids are not observed in nature but are completely fertile unlike mules. Should the parents be considered different species?

3. Evolutionary – Species are individual lines of descent with all their members in the same evolutionary boat.
4. Ecological – A species simply plays some unique role in nature.
5. Phylogenetic – These come in a few different flavors, each claiming to be appropriate for studies of the pattern of evolutionary history (phylogeny):
   • Monophyletic – All members of a species are descendants of a common ancestor unique to that species.
   • Genealogical – All genes within a species were inherited from an ancestral copy unique to that species.
   • Diagnosable – Species possess unique combinations of traits that do not vary.

All of the above proposals sound reasonable, because each has some degree of validity.  When carefully considered, each concept also has unique issues.  Important differences between them are the result of whether they view species as real units of biodiversity (versus arbitrary groupings made for our own convenience), the particular criteria (if any) they stipulate for species recognition, and the corresponding practicability of their application.

So here’s my answer to the species question:  I find the evolutionary species concept theoretically superior, but in practice I would rely on the diagnosable variety of the phylogenetic species concept.  I accept the evolutionary species concept, because it views species as real and fundamental units of biodiversity that result from the natural process of evolution.  This concept primarily explains what species are as opposed to how to recognize them.  It thus admits a variety of types of relevant evidence, including genetic, ecological, behavioral, geographic and morphological.  The problem is that we still need to make decisions about “specieshood” when not all of this data is available, which is most of the time.  This is where I resort to the phylogenetic species concept, because it clarifies what sort of physical properties of an organism may be taken as evidence of lineage independence.  Many such properties are readily observable from dried specimens, which may be the only source of information available, and physical characteristics have formed the basis for species recognition over the past few centuries.  To return to the original question that inspired this post, the issue is not degree of difference but whether the alleged species is an isolated lineage on its own evolutionary trajectory as evinced chiefly by the possession of a unique combination of fixed traits.

In Search of Variation

Eugenia cordata is the most widespread member of a group of species centered in Puerto Rico and the Virgin Islands I call the Lathberry Clade, but, as I found out last month, it is anything but common in Puerto Rico.  It is also an uncommon example of a species of Myrtaceae with two formally named taxonomic varieties:  Eugenia cordata var. cordata, or “lathberry,” and Eugenia cordata var. sintenisii, a.k.a. “white wattle.”  The typical variety is a common shrub of coastal thickets in the Virgin Islands with thick leaves that are heart-shaped (i.e., cordate) at the base.  Variety sintenisii differs primarily in having leaves that are tapered toward the base.  It ranges from Puerto Rico in the west, where it seems to prefer mountain forests, through the Lesser Antilles, where it inhabits drier communities more typical of the lathberry.  The two varieties are otherwise quite similar in having tight clusters of small white flowers borne on naked twigs and a thickened, pale midvein on each leaf.  Having never encountered either of the two varieties in the field before, these were among the top priorities for collecting on my recent field trip to Puerto Rico to study members of the genus Eugenia.

Previous records of var. cordata for Puerto Rico are all from islands off the east coast, including Vieques, Culebra, and Isla Piñeros.  These islands, which boast some of the nicest beaches in the Caribbean, coincidentally were also all once part of a naval base.  To find cordata, we traveled to the Vieques National Wildlife Refuge.  As daylight waned, we arrived at a peninsula in the restricted part of the refuge bordered by rank-smelling mangroves.  We soon found a single plant.  Alas, I had left my camera behind, losing my chance to photograph the living namesake of the Lathberry Clade.  A similar misfortune befell me on my very first field trip three years ago when I saw the elusive Hottea (see my first post).

Wild beach just before sunset, Vieques National Wildlife Refuge.

With one variety down, we began our search for sintenisii two days later at a nature reserve in the mountains.  We were confident of success, because we had a GPS point to guide us to where the plant was found just two years ago. As we began searching the sea of green for the characteristic paired leaves with a tapered base and spicy scent, the sky opened up, giving me the sensation that I was wandering around in an equatorial rainforest.  Although we relocated a large handsome specimen of Myrcianthes fragrans, known as “Simpson’s stopper” in Florida, our party of five failed to find sintenisii after searching in the rain for two hours.

The large Myrcianthes fragrans we encountered.  Look at that bark!

The next day, we made another attempt at Susúa, a quiet forest reserve in western Puerto Rico.  We located the path along the river that we had hoped to follow last year in search of the related Eugenia padronii, and within minutes, I spotted this species.  Following the path further, I was elated to find a large population of padronii, growing much taller than I had known they could.  I began to doubt whether we could find sintenisii there though, so, as the afternoon began, we returned along the river and headed up higher into the mountains to the nearby Maricao forest reserve.  Choosing a path to explore, we continued the search.  Though we found several interesting plants, sintinensii continued to elude us.

View of the dry forest in Susúa.  The Río Loco is at center.

Finally, on the last day of the trip, we headed to a site in the mountains south of San Juan to find another species.  After walking along a trail into the forest for a few minutes, we came upon a sapling growing in the middle of the trail where you could trip on it.  I caught my breath as I realized what I was looking at — sintenisii!  We continued to see it scattered along the path there in the mountains where the species had first been collected over one hundred years ago.

A sapling of Eugenia cordata var. sintenisii.

Mature individual of Eugenia cordata var. sintenisii.

Sometimes you find the plants, and sometimes they find you!

Coalescence—When Evolutionary Time Runs Backwards

Can genes lie?  If misleading partial-truths count, then yes.  Systematists, you see, rely on genes to tell them how species are related to one another by comparing their genetic codes, but the relationships between the gene copies we sample in our studies don’t always match the actual ancestor-descendant relationships between species that are really the subject of interest.  One important reason for this is the phenomenon of coalescence.  A simple explanation of the coalescent process can help us see how genes can tell the truth and be misleading at the same time and suggest ways of dealing with this source of error.

Consider, if you will, an individual gene that exists in many copies in a population of some organism, for example, a flower.  Each variant of a gene is called an allele.  A gene that affects flower color might have two alleles that result in either red or white flowers.  Each individual inherits two copies of a gene, one from mom and one from dad, possibly of different alleles.  In turn, each individual passes on exactly one of those copies to each of its offspring.  Alleles can be lost from a population if none of their copies are passed on to the next generation, and new alleles can arise through modification of existing alleles through the process of mutation.  Thus, every gene has its own genealogy as it flows through a population over time.

Now let’s run things in reverse.  Starting with two different alleles in the present time, we can trace them back through time to a single ancestral allele, in which they are said to “coalesce.”  This is the opposite of how they diverge from one another when time runs forward.  Populations can also diverge from one another such that alleles can no longer freely be exchanged between their members.  When this happens, we say that they are now different species.

An evolutionary tree depicting the relationships between species A, B and C.  The black outline represents the population boundaries that act as conduits for the alleles (orange lines) to flow through time.  Junctions of orange lines are coalescent events.  Notice how not all alleles survive to the present.  Also notice how one of the alleles in A coalesces with the B alleles more recently than with the other A alleles.

 

It’s easy to see that there are different ways in which the alleles in the ancestral population/ species can pass into the two daughter populations/ species.  In the simplest case, each daughter population would have its own unique allele; however, this situation is very unlikely.  More likely is that each population inherits some mix of the alleles present in the ancestral one, meaning that some copies of a gene within a species will be more similar to copies in their sister species than they are to others within their same species.  This is the source of the confusion.  The gene sequences are telling the truth but not giving the whole picture.

Fortunately for systematists, there’s a few things working in our favor.  First is genetic drift, a process that tends to get rid of the confusingly similar copies in different species as they are randomly lost through time.  This means that we may not always have to worry about the more inconvenient implications of coalescence.  Second, we have mathematics.  The time it takes for any two alleles to coalesce in the past is theoretically related to the size of the population.  The larger the population, the longer it takes for two alleles to find each other in the past, because there are more possible paths for them to take through the population.  This relationship allows us to predict how likely it is that coalescent events, and hence gene genealogies, will not coincide with species relationships.  Under certain conditions (large populations and short intervals between speciation events), it is even possible that most of the genes will be misleading about the true species relationships!  Third, since individual genes are inherited independently of one another, looking at different genes gives us repeated trials that allow us to draw conclusions on species relationships backed up by statistics.

All of this goes to show how even the simple process of inheritance can throw a wrench in our efforts to reconstruct the tree of life, but systematists continue to push the envelope by developing new methods for dealing with these complications.  It’s also the big idea behind what I’ve been doing the lab recently.  Now if I could figure out exactly how to analyze the data. . .

Four Steps to Becoming Famous — Sort of

Immortality is elusive.  It’s easier than ever to get a ride, but chariots of fire are in short supply.  One way to achieve a kind of immortality, though, is through making a discovery.  You might never achieve the same fame as Christopher Columbus or Benjamin Franklin, but somewhere your name will be recorded for as long as records are kept.  Such is the case when you discover a new species.  The name of the discoverer, often in abbreviated form, becomes permanently associated with the species name as the “authority,” if only to avoid use of the same name in different senses by different authors.  Of course, you are more likely to be remembered if the species is named after you, but scientific discovery is its own reward, right?  So how do you tell the world that you discovered a new plant species?  Simply follow these four steps to share your discovery with the scientific community:

Describe it. Species are conceptual in nature, so you have to explain in concrete terms what sets yours apart. Although there is no generally agreed upon definition of a species, species are recognized in practice by all of their members possessing a unique combination of readily observed characteristics.  The rules (the International Code of Nomenclature for Algae, Fungi and Plants) dictate that a new species name must be accompanied by a description or diagnosis in either Latin or English that serves to distinguish the species.  A diagnosis is simply an abbreviated description that states only the most important characteristics, often by contrasting a species with a similar one.

Examples of short but valid diagnoses for new species of Myrtus from the West Indies published by Olof Swartz in 1788.  This is why type specimens are important!

Pick a name. Your species needs a proper Latin binomial, which functions like a first and last name for a person. Unless your genus is also new though, all you have to do is come up with the second name, the specific epithet.  These are nouns or adjectives that may be of any derivation whatsoever, but they must be written in the Latin alphabet and conform to some rules of Latin grammar and spelling.  Popular choices for specific epithets are adjectives that highlight a characteristic of the plant (Acer rubrum L. = red maple), names to honor people (Acer maximowiczianum Miq. = Nikko maple, named after famous Russian botanist C. J. Maximowicz), or names that indicate the origin of the species (Acer pensylvanicum L. = moosewood, native to eastern North America, including PA).  Still other epithets derive from the common name of the plant (Psidium guajava L. = guava).  Though the author of a new species has wide latitude, naming a species after one’s self or persons wholly unconnected with botany is bad practice.

Select a type specimen. In case any question should arise as to the identity of your new species, you must also pick a physical specimen to serve as a representative. This is called a type.  It consists of a single collection of the species, generally in the form of a pressed and dried herbarium specimen for plants, permanently conserved in an institution where it is available to qualified individuals for study.  If more than one specimen is prepared from the same gathering and sent to another herbarium, as is usually the case, a single one of these must be designated the “holotype.”  Note that the type specimen doesn’t have to be a good collection or even typical of the species it represents, but it’s advisable to pick one that is.

Publish. If you follow the rules above, you should fulfill the requirement for “valid” publication, but, to be valid, a species must first be “effectively” published. Basically, this amounts to publishing all of the above in a scientific journal.  In principle, anyone can do this, but they have to know what they are talking about in order to pass through the editors and expert reviewers whose job it is to critically evaluate their work.

And that’s all it takes to make your new species “known to science.”  There’s probably better ways to achieve notoriety, but I like a way that rewards those whose careful work has gained the respect of their peers!

Why Plant Relationships Matter: Some Thoughts on Trees

A special message from the Miami Myrtologist:

Dear Botany Enthusiasts,

After a two-month long absence, I’m back.  At the beginning of this year, I felt that I had nothing new to blog about, since I was working on the same things I had been working on and had already written about.  Then things got busy, as they tend to do at times, and I neglected Miami Myrtologist.

The good news is that this time off was productive on several fronts and will give me much to blog about.  In the lab, I have been working on gene cloning, a real hands-on learning experience that I think will provide some interesting insights into the complex evolutionary relationships of island plants.  In the herbarium, I drafted a description of a new species in the myrtle family known only from a small island in the eastern Caribbean and worked with a botanical illustrator to create a more life-like depiction of this species.  I have also been hard at work finalizing the results of the DNA-based phylogenetic study that will form the core of my dissertation.  During Graduate Student Appreciation Week at my university, I practiced giving a short presentation on this study, and I hope to do the same at a scientific conference this summer.  Finally, working behind my desk, I obtained funding for one last Caribbean field trip.  I look forward to sharing this experience with you, my valued readers, later this summer.

For now, I give you some reflections that address “the point” of research in plant systematics.  Given its dependence on public support, this is an important topic for scientists and non-scientists alike to consider.  Thanks for reading!

Peace, Love, & Global Plant Biodiversity,

M.M.

 

Why Plant Relationships Matter:  Some Thoughts on Trees

This week I attended a lecture given by two scientists who helped pioneer molecular plant systematics.  The topic of their presentation was the relevance of large-scale efforts to build a phylogenetic tree of life, i.e. a family tree depicting the evolutionary relationships between every species on earth.  Much of what I do is aimed at figuring out a small portion of this grand tree, and when I explain this in conversation, I am frequently asked, “What is the use/ application/ purpose of that?”  Listening to this presentation, I was encouraged to learn that my talking points in response to this question are similar to the ones these well-respected scientists offered.  I therefore review these points below according to my proclivity for alliteration.

First, it’s important to keep in mind everything plants do for us.  Conveniently, their major uses all start with an “F” sound:  Food, Fiber and PHarmaceuticals.  To these I would add the following:  Furniture, encompassing timber products used for building; Fragrance, including spices and flavorings; and Flowers, themselves a much-valued plant product.  I suppose paper is another major use for plants, but I can’t think of a word for this that starts with the right consonant.  Not to mention oxygen (Fumes?) and ecosystem services (Fringe benefits?), without which we definitely couldn’t survive.

Now to address the utility of research on plant diversity (systematics), particularly their evolutionary relationships (phylogenetics).  After all, you might be wondering why we need to know how apples and oranges are related to eat them; we don’t, of course.  There are nevertheless reasons why it’s worth knowing about plants, even the ones that aren’t medicinal or edible, and their interrelationships.  These can be explained under a few headings all starting with the letter “C”:

1. Curiosity refers to our innate interest in knowing what other living things occupy planet earth. The most fundamental activity of the systematist is cataloguing these life forms. Phylogenetic studies can sometimes help in this process of discovery by leading to the recognition of cryptic species that don’t appear obviously different from their close relatives.
2. Conservation refers to the ethical responsibility many people feel to protect nature from destruction and preserve it for the use and enjoyment of future generations. Systematists provide authoritative identifications as well as basic information on an organism’s distribution, ecology, and life history that facilitate conservation of biological diversity. And it’s hard to look after something you don’t know exists in the first place!
3. Cost refers to the economic benefits of organizing information on living things by classifying them. Modern phylogenetic studies based on DNA sequence data provide the framework for these classifications that we can use to identify hotspots in the tree of life for properties that are useful to us, e.g. plants that produce similar medicinal compounds. This methodology has been critical in the development of many modern crop plants as the genetic diversity of their wild relatives are exploited.  Identification, study, and ultimately exploitation of the wild relatives of economic plants will only become more important in the future as we face challenges such as climate change, increasing global population and soil degradation.
4. Context refers to the unique ability of phylogenetic research to provide the proper evolutionary context for comparisons between species and species groups (clades). This is what the above C is getting at, but, in addition to economic benefits, this context enables a wide variety of comparative scientific studies that yield fascinating insights into the history of life on earth.
5. Culture refers to the importance of different plants and animals in traditions. Most of these have some utility, but others may merely be symbolic. The contribution of systematics in this area is to identify which species are most characteristic of particular places by studying species’ distributions.  When phylogenetic research demonstrates that such species constitute unique evolutionary lineages, they become even more highly valued.  Example of this in plants might be emblematic flora like saguaro cacti (Carnegiea gigantea) in the Desert Southwest or species of king protea (Protea cynaroides) in South Africa that are primarily valued as symbols of their homelands.

Now that you’ve reached the end of my post, here’s a short, animated film that I saw as part of the lecture I attended this week that makes many of the same points:  TreeTender

Enjoy!

Government Taxonomy

Did you know that we have a national curator of pears?  It’s true, and here’s the proof:  Joseph Postman – Curator at the USDA Agricultural Research Service, National Clonal Germplasm Repository in Corvallis, Oregon  This might seem pretty “extra,” but the collection of pear varieties he maintains plays an important role in ensuring the long-term success of U.S. agriculture—if only a small (but delicious) part of it.  But that’s not the only way our tax dollars are at work forwarding plant science.  Uncle Sam also maintains an herbarium of some 5 million pressed and dried plant specimens for us plant taxonomists (people who describe and classify plants) at the Smithsonian’s National Museum of Natural History.  This major collection documents global plant diversity, serving as a resource for scientists from around the world, including myself as I visited earlier this month (pre-partial government shutdown).  Like most other herbaria, it is open to qualified scientists but ordinarily closed to the public.  In the spirit of increasing government transparency, here is what a visit to the U.S. National Herbarium is like.

The National Museum of Natural History seen from across Constitution Avenue.  Not pictured:  the bitter cold.

The National Herbarium, appropriately enough, is housed within the National Museum of Natural History on the National Mall.  Its collection of dried plant specimens fills three large rooms full of cabinets on three separate floors of the museum’s west wing.  At Fairchild, there about 1 ½ cabinets full of Myrtaceae (myrtle family) specimens, mostly from Florida and the Caribbean.  By contrast, the National Herbarium has at least a dozen cabinets of Myrtaceae from all over the New World tropics.

The Myrtaceae collection.  The family starts with the Neotropical genera just past the low cabinet on the left and wraps around the other side of the aisle.

The main goal of my visit was to familiarize myself with some Caribbean species that I hadn’t seen before and shore up the identification of some of my own collections by studying other specimens of the same and similar species.  Although digital images of many specimens at the National Herbarium are available on-line, examining a specimen in person under a microscope is sometimes the only way to see important features of a plant.

The work station I used during my visit.  A stereoscopic microscope is at center, and a stack of specimens for examination is on the far right corner of the desk.  Note the chart giving the sequence of families in the herbarium posted on the cabinet.

One interesting feature of the National Herbarium is its organization.  As in other large herbaria, plants are arranged according to both their geographic origin and taxonomic relationships.  Specimens are grouped first by family, then genus, then major geographical region (e.g. U.S. & Canada, Mexico & Central America, West Indies, South America, etc.) in color-coded folders, and finally by species.  Species are generally ordered alphabetically, while families may follow either an alphabetic or taxonomic arrangement with each family assigned a number.¹ What was interesting to me was the non-alphabetic arrangement of genera according to the system of Dalla Torre and Harms’s Genera Siphonogarum published at the turn of the 20^th century.  This necessitated the use of a cheat sheet to find exactly where in the numbered sequence each genus occurs.

The first 2 pages of the Myrtaceae genus finding guide with handwritten additions and corrections made over the course of 28 years.  Many more could be made, but rearranging everything would be a huge job!

The boundaries of genera are particularly controversial in Myrtaceae, and many new discoveries have been made in the last century.  This means that some of the genera in the original system are no longer recognized, while others (e.g. Hottea) were not yet described.  These must be inserted into the sequence in an appropriate place using letters (e.g. #5579 A for Hottea, thought to be related to #5579 Calycorectes, which is now generally regarded as part of #5578 Eugenia).  All of this makes for a mess—a mess that reflects real scientific progress and job security for taxonomists!

Thanks to the staff of the Botany Department making the collection available to me for study (I even got a temporary security badge with door-unlocking capabilities), I gained several new insights into Caribbean Myrtaceae that will help to fuel my research going forward.

 

¹One popular system is based on Engler and Prantl’s Die Natürlichen Pflanzenfamilien published at the turn of the 20^th century.  This is the most recent complete survey of all the world’s plant families down to the level of genus.  In this system, Myrtaceae is family number 222 out of 280.

The Year in Review

As the year draws to an end and the cold weather settles in, ‘tis the season to reflect on the past year and dream of warmer climes.  With this in mind, I share some of my best Florida plant pictures taken over the past year below.  All are native to pine rocklands that I enjoy visiting periodically.  Pine rocklands, one of the most endangered habitats in the U.S., are characterized by an open canopy of Dade county slash pine (Pinus elliottii var. densa) growing on elevated areas with exposed limestone and little soil.  The understory is typically dominated by saw palmetto (Serenoa repens) as shown below.

Pine rockland

The limestone rock of pine rocklands is a porous, whitish substance that makes up much of peninsular Florida.  It is easily eroded by water, which leads to pockmarks and jagged edges on the surface as well as sinkholes.  It’s not very hospitable for plants either, being poor in available nutrients and excessively well-drained.  Pine rocklands are nevertheless one of the most botanically rich habitats in the Sunshine State, including a number of plant species found nowhere else.  Such challenging environments tend to generate biological diversity as organisms adapt to the adverse conditions and become isolated from their relatives in other environments or widely separated patches of similar environments, e.g. pinelands in the Caribbean islands.  And without further ado:

Calopogon tuberosus

This beautiful orchid, a grasspink (Calopogon tuberosus), was photographed in Everglades National Park in a wet prairie on the edge of a pine rockland.  Florida has a surprising array of both ground-dwelling (terrestrial) and tree-dwelling (epiphytic) orchids.

Metastelma blodgettii

Blodgett’s swallowwort (Metastelma blodgettii = Cynanchum blodgetti) is a dainty and easily overlooked twining vine from pine rocklands in southernmost Florida and the Bahamas.  Like other members of the dogbane or milkweed family (Apocynaceae), it exudes a milky sap when the leaves or stems are broken.

Geobalanus oblongifolius

Ah yes, the gopher apple (Geobalanus oblongifolius = Licania michauxii).  This low-growing shrub is more of a botanical curiosity than a looker, but so are some of my favorite plants.  It is one of two species of a family of tropical trees (Chrysobalanaceae) native to the U.S.  The other species is the commonly planted coco plum (Chrysobalanus icaco), which, as its common name suggests, has edible purple fruits.  Though not limited to pine rocklands, or even Florida, the gopher apple blends in with the shrubby oak saplings common beneath the pines.  The fruit, distinctly not an acorn, gives it away.  Strangely, Chrysobalanus is a name of Greek origin meaning golden acorn.

Chiococca alba

Snowberry (Chiococca alba) is another widespread species.  It is a member of the huge, mostly tropical coffee family (Rubiaceae) with clusters of lovely little bell-shaped flowers that vary in color from yellow to white.  According to the Florida Plant Atlas entry for the species, the photographed plant is a diminutive form of uncertain taxonomic status; i.e., it might be a different species!

Aletris bracteata

Had to include colicroot (Aletris bracteata) too, because it is a member of an obscure group of monocots, the bog asphodel family (Nartheciaceae).  The spikes of white flowers, though also not particularly showy, have a nice effect scattered through the grass that my pictures just couldn’t capture.

Mosiera longipes

Last but certainly not least is long-stalked stopper (Mosiera longipes), a member of the myrtle family (Myrtaceae)!  Also known as Florida guava, this species has sweet blackish fruits and is indeed closely related to the common guava in the genus Psidium.  Mosiera is a genus characteristic of the Caribbean, with most of the species endemic to Cuba, and this species was the first to be placed in it.  Long-stalked stopper is one of eight species of the myrtle family native to Florida and the one most likely to be found in pine rocklands.

Now you know why I like to visit pine rocklands.  They’re a great place to spot plants and escape the urban jungle in a pine-scented oasis.  Here’s to more great plant sightings in 2018!

Labels, Latin and Localities

The thrill of the hunt.  It’s part of what makes plant collecting expeditions so exciting.  There’s no chase or blood; instead, the suspense of whether the quarry will resolve itself out of a tropical sea of green.  Of course, with all the plant species in a biodiversity hotspot like the Caribbean, a botanist needs some directions to successfully track down a plant.  How does this work in the 21^st century?

The ultimate source of all verifiable information on where a plant can be found comes from the notes of previous collectors.  Because of how important this information is, it is recorded directly on the labels attached to dried plant specimens.  These labels also include the date of the collection, the name of the collector, and a collection number, which is usually a running total of how many collections that person has made.  Beyond this, a label may provide information on the habitat in which the plant occurred, including associated species, and features of the plant which cannot be represented on a sheet of paper (e.g. growth habit) or that are altered upon drying (e.g. flower color or the size of fleshy fruits).  Though it sounds strange, I once heard a botanist declare that the least important piece of information on the label is the name of the plant!  The reason is that the name is always subject to change as the identity of the plant is reassessed or the species is reclassified.

Example of a label from a specimen of Myrtaceae photographed at the Carnegie Museum of Natural History. This is collection number 1528 of P. Sintenis from Puerto Rico. In June 1885, I. Urban identified it as Eugenia eggersii, a species described by Kiaerskou. It was found in the forest in the Sierra de Luqillo.

When starting a search for a plant from scratch, it’s often best to check floras and taxonomic treatments (monographs and revisions) specific to the group of plants you’re interested in first, as these will contain lists or summaries of authoritatively identified plant specimen label data.  The problem is that floras often are often not specific enough, and there may not be a recent treatment covering the plant you’re interested in.  In this case, one can go directly to the source by searching through the specimens, a process greatly facilitated in the 21^st century by museum collections digitization initiatives.  Though some of the larger plant collections have digitized many of their holdings (notably all Caribbean specimens at the New York Botanical Garden), most of the world’s plant specimens are not online.  Sometimes the best strategy is thus to check the original description (protologue) of the plant in question.  For many of the rare species I am interested in the Caribbean, especially from areas like Haiti that haven’t been collected recently, this is the best approach.

By way of illustration, here is an example of the information I had to go on for one species I looked for on my recent field trip to Haiti:

Haiti, Massif de la Hotte, in parte occidentali prope Les Roseaux in collibus calcariis ad habit. Léger cr. 400 m. alt.: n. H10432 (typus, ster.), ibidem prope Tiburon in Morne Sentier in sylvis 750 m. alt.: n. H 10578 (ster.)

As you can see, knowing some Latin and the conventions of taxonomic literature helps.  The next challenge is finding the locality.  I admit that I was not too optimistic about finding the place known as “habit. Léger” 100 years ago.  But evidently Léger made his mark, because it didn’t take long to find someone in the town of Les Roseaux who know where that was.

Les Rouseaux, Dep. Grand’Anse, Haiti

The real trick, though, is finding the plant.  This is where a GPS that gives altitude readings comes in, because it helps you know when you can stop climbing and look around.  On a real hunt, sometimes you find your prey and sometimes you don’t.  This time we were unsuccessful, but we did find some other inhabitants of “habit. Léger,” including a striking red passionflower and a lovely member of the nightshade family only found in Haiti, Brunfelsia picardae, so I wasn’t too disappointed.

Brunfelsia picardae

Passiflora sp.

 

That, believe it or not, is how we go about finding rare plants in the Caribbean in the 21^st century:  a little Latin, a little luck, and no small amount of looking.  Then we take a GPS reading at our arrival point, thereby linking the plant’s precise location with a variety of associated spatial data and ruining half the fun for the next guy!

Following Ekman

“Why would you want to go there?”  This question followed us around southern Haiti on my latest Caribbean field trip on our way up steep mountain slopes or to remote areas.  In response, our Haitian colleague frequently had to explain to the local people that we were seeking to relocate a plant found there nearly a century ago by the intrepid Swedish botanist, Dr. Erik L. Ekman; that is to say, if we’re crazy, Ekman was crazy first!  It’s worth considering the story of this fascinating figure whose work still informs botanical field research in the 21^st century, including my own recent efforts to collect members of the myrtle family from Haiti.

Statue of Ekman holding a plant press at the Jardin Botanico Nacional “Dr. Rafael M. Moscoso” in Santo Domingo, Dominican Republic.

Ekman, who was supposed to travel to Brazil, was sent to Haiti through the intervention of Professor Ignatz Urban, an eminent German botanist studying the flora of the Caribbean.  Ekman traveled via Cuba, where he was held up for three years due to political unrest (including WWI) and an outbreak of bubonic plague on Hispaniola.  In the meantime he made 20,000 collections that resulted in the description by Urban of 1,000 plant species new to science.  When he finally arrived in Haiti in 1917, Ekman made two failed attempts to scale the high mountains of the Massif de La Hotte in southwestern Haiti, contracted malaria, and returned to Cuba after a few months.  Nevertheless, his collections, received by Urban in 1920, contained about 80 new species and were sufficiently interesting to induce Urban to prevail upon the Swedish Royal Academy of Natural Sciences to recall Ekman from Cuba to continue exploration of Haiti, especially the high mountains of the Massif de La Hotte.  According to Ekman, “Like most human beings I dislike to do what I am told to do and so I resolved to climb all other mountains in the Republic first and the La Hotte, if ever.”¹  Happily for us and for Urban, that is exactly what he did.  In 1924 Ekman returned to Haiti and spent the next four years scouring the country for—and finding—new plants, eventually summiting one of the twin peaks of the La Hotte range, Morne Formon, with his friend and colleague the American botanist Dr. Henry D. Barker.  In December 1928, Ekman left Haiti for the Dominican Republic, where he died collecting plants in 1931, the same year as Urban.

Pimenta (Myrtekmania) filipes, a species discovered by Ekman in eastern Cuba.

Ekmanianthe longiflora, a tree with long white flowers in the trumpet creeper family.

The life and work of Ekman are commemorated by no less than eight plant genera (in addition to numerous species) that bear his name.  This includes Myrtekmania, a genus of the myrtle family Urban named in his honor whose species are now classified under Pimenta.  Ekman has also been immortalized in The Magic Island, an interesting book about American author William Seabrook’s exploration of voodoo in Haiti.  Seabrook devoted two chapters to his interactions with this botanical legend, whom he initially mistook for a bum as he napped in the open in his tattered field clothes.  After tagging along on one of his grueling field excursions, Seabrook portrays Ekman as an eccentric, and at times, impish mountain goat completely obsessed with botany.  Whatever we make of his personality, Ekman’s fruitful endurance of all manner of hardship and drive to boldly go where no botanist had gone before are truly inspirational.

Systematic botany is a discipline with a deep awareness of its past, as the work of our predecessors remains largely relevant over time.  This is clearly seen in the case of Haiti, one of the very first places in the New World tropics to be studied by botanists, but which few botanists have visited since the time of Ekman.  Ekman’s collections from 100 years ago thus still form the basis of much of what we know about the flora of Haiti today, hence our repeated explanations invoking his name.  And after a century of increasing human pressure on the environment, many of his discoveries remain to be recollected as a challenge to modern botanists.  Perhaps this can spur me on when I’m climbing up an impossibly steep slope to look for plants and feeling more like a Swedish meatball than a great Swedish botanical explorer!

 

¹ Quotation from Ekman, E.L. 1926. Botanizing in Haiti. U.S. Naval Med. Bull. 24(3): 483-497.