Sunday, February 19, 2017

Mosses of Central Florida 19. Rosulabryum capillare and R. pseudocapillare

Although the leafy shoots are buried within a
different moss, the presence of this Rosulabryum
is evident by the abundant and very large sporangia,
or capsules.
[For other mosses in this series, see the Table of Contents]

Like many other groups of mosses, those in the family Bryaceae are difficult to identify.  The available keys are highly technical and difficult to for non-specialists to follow.  The two species of Rosulabryum are presented together here because of those difficulties. R. capillare (Hedwig) J. R. Spence (Bryaceae) is common throughout North America, including Canada and our western states.  According to Flora North America, it is not found in Florida, but the related species R. pseudocapillare (Besch.) Ochyra takes its place.  However, numerous collections made in Florida have been identified by experts as R. capillare, along with many labeled as R. pseudocapillare.

Here, some leafy shoots have been isolated.
They are upright and radially symmetrical,
and the stalks of the sporangia arise from
the bases of the shoots.
The species of Rosulabryum found in Central Florida is common and produces abundant nodding, nearly cylindrical sporangia (also called  capsules) in the springtime.  It can be found most readily in wet soil at the margins of receding ponds, forming mounds of upright stems. It might almost be considered weedy, as it also pops up readily in pots containing wet, organic soil, and in wet soil along sidewalks.

Rosulabryum was formerly included in the genus Bryum, having been segregated out on details that are hard to follow in the formal keys.  In Florida, only Bryum argenteum remains in the original genus, which incidentally gives its name to the entire clade of non-vascular plants we call Bryophytes.  B. argenteum differs from Rosulabryum in its more compact growth form, its grayish coloration, and leaves that press flat against the stem when dry.  The dried leaves of Rosulabryum twist around the stem.

Nearly ripe sporangia of Rosulabryum
are cylindrical and bright green.
The large, nodding sporangia of Rosulabryum are distinctive locally, but characteristic of many members of  the Bryum family. The other segregate from Bryum found in Florida is Gemmabryum, but it apparently forms sporangia less often than Rosulabryum, relying more on asexual bulbils and gemmae for reproduction.  The leaves in Gemmabryum are also said to be pressed flat against the stem when dry, as in Bryum argenteum, rather than being twisted like in Rosulabryum.

Leaves of Rosulabryum, like other members
of the famly, have a strong midrib (or costa).
Leaves in the Bryaceae have a strong midrib, and the leaf cells are mostly large, more-or-less rectangular or rhomboidal in shape, thin-walled, and with numerous distinct chloroplasts.  This, along with the upright, mound-forming stems and the nodding sporangia, makes members of the family fairly easy to recognize, though the genera and species are more difficult to distinguish.

Leaf cells of Rosulabryum, are thin-willed,
revealing many distinct chloroplasts within.



Monday, January 30, 2017

Teaching biodiversity

The biodiversity crisis is one of the most pressing issues facing mankind.  But what is biodiversity? How does it come about?  Why are there so many kinds of organisms?  And what are the consequences of lost biodiversity?  Sounds like something we could devote a whole course to in our undergraduate curriculum.  But when we do, it's usually only to a handful of upper level ecology students.  What about our general student population, all those pre-meds we educate, or the public at large?  We would like our general citizenship to be well-informed on the dimensions and importance of biodiversity, but at the very least, our own biology majors should be not only informed, but also advocates.  How are we all doing on that?

The one, and sometimes only, opportunity we have to reach all of our undergraduates is in freshman biology.  A second opportunity comes if we can get students to take an organismal course like introductory botany, invertebrate zoology, mycology, or entomology.  The following suggestions apply equally well to all such courses, but I will focus on Freshman Biology, which in my university is taught in two separate one-semester courses: Cellular Processes and Biodiversity.  We use one of the standard large college texts for introductory biology.

The second course, Biodiversity, sounds good, but it has an ambitious amount of material to cover.  It is divided roughly into three sections:  Evolution, Diversity, and Ecology.  The section on Diversity, which might get five weeks out of the semester, is usually a rapid march through the kingdoms and phyla.  Plants usually only get 1-2 weeks of discussion in lecture,  fungi even less, more often than not by an instructor who has not had much training in botany or mycology.  The sections on animal and plant biology in the textbook are largely ignored in our courses, but they contain much additional information that can and should be brought in to help elucidate biodiversity issues.

The net result is that after this course in Biodiversity students have only a superficial introduction to diverse kinds of life, and have no real understanding of why there are so many different kinds of organisms.     The coherent biodiversity message will only  emerge if an experienced and skillful instructor is motivated to do so, and willing to synthesize material from different parts of the book.  The more we can integrate our discussions of evolutionary and ecological principles with questions about biodiversity, rather than treating them as three separate topics, the better. This is a tall order for the limited time available in a freshman course, so you have to choose your battles carefully.


Here are some ideas, with links to my blog essays that discuss these topics in detail:

1.  Think in terms of  adaptation.  This is the key concept  that links evolution, ecology, and biodiversity together. Adaptation is what results from the evolutionary process, it defines how organisms interact with their environment, and it is what differentiates the distinctive lifestyle of one organism from another.  Organism A is different from organism B because, since their common ancestry, they have had different adaptive histories, and have diverged into different lifestyles.  They have come to live in different environments  or to survive in the same environment in different ways.
The flowering structures of skunk cabbage are
adapted for getting a jump on the spring
flowering season by generating sufficient heat
to melt their way through the remaining snow.
Photo by Sakaori, from Wikimedia Commons

2.  Every feature has a function.  Everything we see in an organism, from the shape of a leaf to the color of tail feathers in birds, has some adaptive function, or did sometime during the adaptive history of the organism.  There is a story for every characteristic feature of a species.  Pollination biology presents many attention-grabbing examples.

3. "What good is half an eye?" Make use of some of the great questions posed by anti-evolutionists (though answered wrongly by them).  By focusing  on a single topic, like vision, one can trace the origins of light detection in bacteria, through the simple eyespots of protists, the simple eyes of flatworms, and then the diverse kinds of eyes found in cephalopods (squids, octopi), insects, and vertebrates.  There never was half an eye, always light detecting systems that became more complex and varied over time.  We can even bring in plants with their light-detecting systems  involved in phototropism (bending toward light), and photoperiodism (determining when plants bloom.)

 4. "If humans evolved from apes, why are there still apes?"  Another great question that illustrates the diversifying nature of evolution.  From the common ancestor of chimpanzees and humans, the chimp lineage continued to hone their adaptations for life in the forest, while human ancestors adapted for life in the open savanna, with skeletal changes that allowed them to stand upright and walk comfortably on two legs.  Students really take interest in human evolution, and so it is worthwhile to spend time on it.

Animals are eating machines, with mouth and eyes at the
front end, and locomotory organs along the side. Their
food resources are in compact packages - other organisms -
that they digest internally.
2. "What is the difference between plants and animals?"  I always began my botany classes with this question.  Almost everyone starts with the observation that plants are photosynthetic and animals eat stuff. True as it is, it is only  the beginning. The next thing that might come up is that animals move and plants don't.  Then as an instructor, you ask "why?"   Asking why is not to be anthropomorphic.  It's really asking "what are the adaptive advantages for plants not to move?"

Plants are anchored in one spot and create
branched systems above and below ground for
gathering diffuse resources. Meristems continually
create new roots, twigs and leaves.  And materials
are transported internally by manipulating water
pressure.

One can then direct the discussion to the stationary, indefinitely branching body of a plant, adapted to create  an expansive antenna system for gathering light and other diffuse resources, in contrast to the discrete bodies of animals with mouth and sensory organs at the front end, and locomotory organs along the sides.  One must then discuss the system of meristems that enable varied plant architectures built of repetitive leaf-bearing units, and the hydrostatic nature of plant cells and plant processes that substitute for muscular activity in animals.



3. Why are there no moss trees? Everyone knows, at least by the time they get to college, how animals make babies.  The varied equipment and various strategies for getting sperm and egg together are a wonderful theme for exploring animal diversity, but how do plants do it? Plant (or fungus) reproduction, however, is always a challenge.    If you're stuck in one spot, and a potential mate is 50 meters away, how do get your sperm to her?  The astute student will immediately shout "pollen grains."  But how many know that there are actually sperm cells produced within pollen grains, and that pollen grains, and the structures that house the eggs are actually tiny. haploid individuals?

Eggs and sperm cells in ferns are produced on a
separate, independent, short-lived plant
(gametophyte)  that develops from a spore
released from the main plant (sporophyte).
Meiosis occurs during the production of the
spores, rather than in the production of gametes.
From Haupt, A. W. 1953. Plant Morphology.







That brings up the dreaded life cycle.  Students hate them and instructors who don't know their significance tend to skip over them. Memorizing a life cycle does not explain why life cycles exist.  What is the adaptive value of having separate tiny haploid plants to bear the sperm and eggs?  The place to begin is with ferns.  There is adaptive value in breeding with distant, genetically different individuals.  That would be impossible if the fern plant produced sperm and egg cells directly, as sperm cells on dry land can't get very far.  So instead, it produces spores, which can easily disperse over great distances.  Often enough, spores from genetically different ferns land together, These spores then germinate to produce tiny gamete-producing plants that can breed with one another.  The fertilized eggs then develop into a new fern plant.




The leafy, long-lived phase of a
moss life cycle is the egg and
sperm producing gametophyte.
The simple sporophytes consist
only of a single sporangium and
its stalk, which develops from
the fertilized egg, and which
remains attached to the gametophyte
plant for its short existance.
The answer to the question about moss trees is that a moss is actually a gamete-producing plant, and must remain small so it can mingle with genetically different plants for successful reproduction.  Mosses lack independent spore-producing plants, having instead small diploid spore-producing structures that emerge directly from the fertilized eggs, but remain attached to the parent plant. Thus there is no part of the moss life cycle that can get really large.

 Pursuing these sorts of discussions is of more value than memorizing the characteristics of all the phyla of invertebrates, or the differences between club mosses and horsetails.  Horsetails can be brought in, however, as an early example of the kind of multiple elongating (intercalary) meristems used by bamboos for their rapid growth in height.(convergent evolution).  Ultimately, we can try to understand why there are so many kinds of plants, and how to avoid the extinction of all those species.





Saturday, October 15, 2016

Endangered plants, the population bomb, and politicians running for office


Cycads are gymnosperms that have survived from the dinosaur
era.  They are increasingly at risk of extinction from poaching
and habitat loss.  These Encephalartos brevifoliolata
from South Africa are already extinct in the wild.
Photo by Piet Vorster, CC BY-NC-SA 4.0 .
The cycad Encephalartos brevifoliolata is an endangered species.  In fact, it is already extinct in the wild, surviving only as a few specimens that had to be moved to a secure location.  Habitat loss and poaching for the horticultural trade threaten many species of cycads. These ancient gymnosperms are among the relatively few plants that exhibit complete gender distinction. Individual plants are either male or female, and as it happens, the surviving members of this species are all male.  Even if there were a female among them, their gene pool would be severely restricted, and future generations would be highly inbred.  With such limited genetic variation, recessive genetic defects are more likely to be expressed, and the entire population much more likely to succumb to disease or environmental change. Cacti, orchids, and carnivorous plants are other groups particularly threatened by poachers, but many other kinds of plants are equally threatened by loss of natural habitats to logging, agriculture, and "suburbanization."

More familiar examples of this are of animals.  Aside from the loss in numbers and other threats, concerns about the rare Florida panther center around its minimal genetic variation.  Animals in more vulnerable 
regions, such as rhinos, tigers, snow leopards, great apes, etc. face more immediate threats, but those that survive, possibly only in zoos, will face the genetic inbreeding problem as well.   Under such genetic constriction, the future of these species is in question.

Carnivorous plants around the world, like this Sarracenia rubra
in north Florida, face habitat loss and poaching by hobbyists.  
According to the Center for Biodiversity, a significant percentages of the Earth’s plants and animals are at risk of extinction, including 50% of the species of primates.  An estimated 1000 species of plants and animals that have already gone extinct under the watch of humanity (see The Extinction Crisis).  Again, animals are more familiar – dodos, passenger pigeons, etc., but 123 plant species have also been officially documented as going extinct in historical times (according to Wikipedia).  This is not to mention also the fact that possibly only half, or less, of the species of living organisms on this planet have even yet been documented by scientists, so we don’t know many that have already gone extinct or are endangered.  The present threat to the existence of organisms of all types, called the biodiversity crisis, could become a mass extinction greater than that in which the dinosaurs became extinct.

What are the consequences to the global ecosystem of plant and animal extinction?
This Dendrobium bracteosum was salvaged from the
branches of a tree felled for the timber industry in
Papua New Guinea in 1971.  Though widely cultivated,
what the fate of this species in the wild is today,
I do not know.
The loss of any species disrupts and simplifies the complex interactive web of life around us.  A plant that goes extinct may be the host or food source for dozens of other organisms, and likewise, an animal may be an important link in the food chain or a predator that keeps other animal populations in check.  Destabilized ecosystems are less productive, subject to wild fluctuations, suffer soil erosion, and become overrun by tough, weedy species of no use to anyone.  Loss of forests and the poisoning of photosynthetic algae in the oceans diminishes the replenishment of oxygen in our atmosphere, and the removal of carbon dioxide.

Why is all of this happening?  We might point to lack of regulation and enforcement, poor land management and forestry practices, human greed, and maybe the erroneous belief by many collectors that they are helping "save" rare species by growing them in their backyards.  But clearly, the growing human population, with its expanding demand for farmland, wood, clean water, and other natural resources, is directly related to the loss of natural habitats required by the others species we share this planet with. 

In 1968, Paul Ehrlich and his wife Anne (uncredited at the time) published The Population Bomb (Sierra Club/Ballantine Books, ISBN 1-56849-587-0), which warned of the dire consequences of uncontrolled and excessive growth of the human population.  They predicted widespread famine and other disasters as early as the 1970’s. The predictions were based on sound biological principles.  Every species tends to increase in numbers, because individuals have the potential to produce many more offspring than needed for their replacement.  In a balanced ecosystem, populations of each species are kept in check by limited food supply and other essential resources (e.g. nesting sites for some animals), by disease or predators, or by fouling their own environment.

The organ pipe cactus, Stenocereus thurberi,
is one of hundreds of cactus species that are 
endangered.
Photo by Lars Hammar CC-BY-NC-SA 2.0
Though the Ehrlichs’ may have been off on the timing of some of their predictions (see their recent review article), the need to bring the human population under control is accepted by scientists and humanitarian groups in general.  The principle objections come from people who fear draconian governmental population control measures, or the impacts of no-growth economics.  Again, I can’t do a full review here, but a simple google search for either “overpopulation” or “underpopulation” will bring up a number of links (yes there are people who believe that we, at least in some countries, are underpopulated). 

Before I move on though, I must remark that while the world may not appear to be overpopulated from the biased perspective of affluent America, the 760 million people in the world who are currently undernourished, the 8,350,000 people who die of starvation each year (Worldometers), or the perennially impoverished people of Haiti who just suffered devastating losses from Hurricane Matthew, might beg to disagree.


Expanding numbers of desperately poor people encroach upon national parks and other wildlife preserves to find a means of livelihood, further endangering species and disrupting natural ecosystems.  Maybe we can support more people on this planet, but only by converting ever more wild land to food production.  As we attempt frantically to increase our food supply, we cut down more forests, irrigate deserts, and even encroach upon estuaries and marine habitats.  We also use more fertilizer, pesticides, hormones and antibiotics, keep animals in small cages, and continue to genetically modify our food crops. Watch the streaming statistics on Worldometers for a few minutes, you can also see that almost 4 million hectares of forest have been lost this year, and over 5 million hectares of soil have eroded away, along with other disturbing numbers that continue to increase.  And despite all the technological advances, if population continues to grow, we'll back to where we started, but with even more starving people, less wild land, and fewer species of plants and animals.

Adding the problems of air and water pollution, nuclear leaks, toxic waste dumps, and climate change, we are not only fouling our own nest, but that of wild plants and animals as well.  Coral reefs are dying around the world, as well as forests in the Appalachians and California mountains, honeybees are being poisoned, and tree frogs are dying from the effects of pollution.  As sea levels rise and ice caps disappear, not only are polar bears threatened, but also coastal estuarine communities (breeding grounds for many commercial fisheries), sea grass beds and lowland swamps, not to mention the billions of people who live in coastal cities. 

The human suffering is  front and center in our collective humanitarian consciousness, and protecting rare species may seem to be a luxury for the benefit of the affluent, but they are actually both manifestations of the same central problem.  Bringing population growth under control will benefit both people and biodiversity, and the sooner we do it, the better.

Instead of just trying to keep up with increasing population size with ever more technological fixes, maybe we should be asking how many people can the Earth sustain while providing a just and equitable distribution of resources to all of our inhabitants, and while maintaining a viable, biologically diverse ecosystem with which to sustain ourselves.  I would think that, just maybe, we already have enough people on this planet, maybe more than it can sustain cleanly with renewable resources over the long run. Perhaps even a small decline would be helpful in taking care of everyone already here and getting back into balance with our natural ecosystem.  After all, there are already 7.5 billion of us.  We have huge, possibly insurmountable problems to solve, which are only exacerbated if the population continues to grow.  So reducing global population growth should be on the table as a  topic of public discussion, right next to all the other problems that need to be solved. 

But it isn’t.  Outside of academic circles and activist blogs (both pro and con), the population problem is hardly ever mentioned.  It’s not in the mainstream media or in politics. And that brings me to the third part of my title.  As we face elections here in the U.S., or as some of you face them elsewhere, we must choose candidates who respect science, who are aware of the impact of population growth on world justice and on our planetary ecosystem, and who are willing to study and discuss these issues seriously.  They must also take the search for sustainable economics seriously.  Those who deny the existence of climate change and rising sea levels, who want to do away with environmental protection agencies, who oppose treaties on clean air and reduction of carbon emissions, and who want to open up national parks and other wild lands to mining and other economic exploitation, just don't get it, and must be rejected. 

Tuesday, July 5, 2016

Mosses of Central Florida 18. Bryum argenteum

The fine, compact cushions of Bryum argenteum are a distinctive grayish-
green.  This specimen was collected in gravel at the base of a palm tree along
a walkway above a saltwater channel in Tampa (Essig 20160503-1 (USF).
Bryum argenteum Hedw. (Bryaceae) forms compact, fine-textured cushions in exposed areas of poor soil, gravel, or even concrete. It is easily recognized by it's grayish green color, in contrast to the bright green of most other members of the family in our area.  It is the only member of Bryum in Florida.  Other species formerly included in the genus have been segregated out into other genera, including Gemmabryum and Rosulabryum.  It is distinguished from these latter genera by its smaller, more compact dimensions, and the leaves that are more-or-less pressed to the stem, like the scale leaves of a juniper.
The leaf cells of Bryum argenteum, are large, thin-walled,
and filled with chloroplasts. 
Like other members of the family the cells of the leaf are large, and thin-walled, and there is a prominent midrib.  Also very distinctive in this family are the nodding capsules.  This species does not produce capsules very often.  The accompanying picture of capsules is from a specimen collected in Bronx, NY.
The capsules of Bryum argenteum, like
most members of the family Bryaceae,
are symmetrical but nodding by a bend in
the uppar stalk.  From Ahles s.n.,
Bronx, NY 1949 (USF)

Wednesday, June 22, 2016

Mosses of Central Florida 17. Sphagnum strictum

Sphagnum strictum occurs in dry woodlands, and forms whitish branch heads
that are more compact than those of S. palustre.
Sphagnum strictum Sull. (Sphagnaceae) occurs throughout northern Florida, as far south as
Collier County.  It is distinctive within the local species for its dry habitat preference and tolerance of desiccation. It occurs in oak hammocks and other dry woodlands, on dry, sandy soil.  It most often has a very whitish color, as its leaves consist of large water storage cells within which the photosynthetic cells are confined to very narrow strands. 


When dry, the branch heads become more feathery.  Photo by Alan Franck.
(from Franck 3787 (USF)
Sphagnum strictum produces sporangia in the spring, while S. palustre produces them in the Fall. 
The reddish sporangia of Sphagnum strictum appear
in the spring.

The leaf of Sphagnum strictum is composed mostly of large water-storage
cells, which appear as empty.  The cells are reinforced by fibrils wrapped
around each cell.  What appear to be thick cell walls are actually the very
narrow photosynthetic cells.

Mosses of Central Florida 16. Sphagnum palustre

The leafy shoots of  Sphagnum palustre consist of
a compact head of short shoots, with a ring of
longer shoots hanging below.  Each shoot in this
complex consists of a series of closely spaced
ovate leaves.
Sphagnum palustre L (Sphagnaceae) is one of the most common, and most abundant sphagnum mosses in central and northern Florida.  Outside of the state, it extends into to the boreal zone of Canada, and contributes to the massive sphagnum bogs found there.



 Sphagnum species are notoriously difficult to identify, however, and it is probably safe to say that only Sphagnum specialists can use the technical keys to identify a specimen, and even then there is uncertainty and disagreement.  The characters that distinguish particular species, and even whole groups of species, are anatomical in nature, requiring specialized skills to view and interpret.




On a local level, however, particularly in Florida, there are typically only a few species in an area, occupying slightly different habitats, and differing in the size, shape, and coloration of the leafy shoots.  25 species are presently known to occur in Florida, 18 of which extend into central Florida.  Few extend much further south than Hillsborough and Polk Counties, but P. palustre  reaches its southern limit in Highlands County. These numbers and distributions are only approximate, as the herbarium records involved have not all been verified by specialists.  Additional collecting will also add to our knowledge of the distributions of species. 


An extensive colony of Sphagnum palustre near the Hillsborough River, occurring in a flat
seepage zone.
Sphagnum palustre is distinguished from other species in Hillsborough County by its larger shoot size, and the distinctive shape of its terminal cluster of branches. It also occurs, in our area, in a unique habitat zone: in relatively flat, continuously wet zones, such as a seepage area, which is neither often flooded nor completely desiccated.  S. palustre produces sporangia in the Fall. 


Another common species found nearby, S. strictum occurs in drier habitats and has smaller, distinctly whitish clusters of shoots (profile of this species to follow immediately after this).  A third species, yet to be identified, occurs in intermediate habitats.





Although the species are difficult to identify, the genus is unmistakable, particularly with a quick look at a leaf under a microscope.  The leaves are just one cell thick, but differentiated into two kinds of cells.  The green, photosynthetic cells are long and narrow, and form an interconnected network between much larger water-storage cells.



Special note: the mosses have now been added to the Atlas of Florida Plants, where you can see the county by county distributions of each species.  We are also slowly adding photographs to the database. 

Thursday, May 12, 2016

How to identify a plant

When you encounter a plant that you do not know, it is natural to want to know its name.  In my previous post, I described some ecological disasters that resulted from scientists misidentifying plants used in experimental studies or in habitat restoration.  I also provided a reference where numerous incidences of accidental poisoning have occurred through consumption of misidentified food or medicinal plants.

Can you tell the difference between the two specimens below? Two people in Italy were recently hospitalized for confusing them.  The one on the left is fennel, the one on the right is poisonous Hemlock, two species out of hundreds in the carrot family, Apiaceae. Though there are clear differences, including flower color and leaf shape, you would have to know them from experience or have them identified by an expert before using them.
Photo by Alvesgaspar - Own work, CC
BY-SA 3.0, httpscommons.wikimedia.
orgwindex.phpcurid=15855012
Photo in public domain,
https://commons.
wikimedia.org/w/index.php
?curid=2740278
its name.  In some cases, it may be critical to ID it correctly: if you're using a plant in a scientific study, if it's something you may eat or take as a medicine, if your child has eaten something that might be poisonous, or if you're selling plants of some supposed horticultural or medicinal value.  The list goes on and on.  In my

So what do you do?  If it's important, you at some point will have to consult an expert.  You can use available tools to identify it yourself, or at least narrow down the possible identities.  If you have a deep interest in plants, learning identification skills can be time well spent.  It will sharpen your eye for detail and deepen your understanding of plant diversity and adaptation.  If, however, you are a mother in a panic about what your child just put into his mouth, skip this step!

In either case, you need to gather as much baseline information as possible:

1. Is it wild plant, or a cultivated one?  There are different tools for these fundamental categories.

        If it is a wild plant, and you know where it came from, you've already
greatly limited the number of possible plants. There are typically field guides, keys, pictorial guides, and specimen depositories (herbaria) for specific regions of the world, that you can avail yourselves of.

        If it is a cultivated plant, where it was growing is also important.  Plants cultivated in south Florida are quite different from what can be grown in Maine, and there are often regional guides for cultivated plants.

2. What plant parts do you have to work with? Though a good forensic botanist may be able to ID seeds, pollen grains, or wood fragments, generally a good sample of the foliage as well as the flowers and/or fruit is necessary for identification.  Photographs are helpful, but the actual physical material is important for examining small details.

If the above information and materials are fairly complete, you are in a good position to seek out an appropriate expert, or plunge on yourself.

The primary job of plant taxonomists is to inventory the plant
life of the Earth.  Here, taxonomists Heinar Streimann
and Peter Stevens work with local villagers to pack up
plant materials that will be dried and deposited in
 around the world as reference specimens.  Photo taken on an
expedition to Aseki, Papua New Guinea in 1972. When not
in the field, taxonomists continue their research in plant
diversity, teach students, and identify specimens sent in by
others. 
A.  Finding an expert.  Plant identification experts are called taxonomists or systematists, and they reside primarily at herbaria and botanical gardens. If there is such a facility locally, that will be your first contact. In most states, there is at least one major herbarium, usually at the primary state university or at your state's designated agricultural college.  In big states, like California, Florida, Texas, and New York, there are several major herbaria.  A local county agricultural extension agent may know many of the plants cultivated locally, and can also direct you to the nearest herbarium.  Outside of the US, each country has a similar network of regional and national herbaria.

Once you locate a herbarium and confirm that they are willing to look at your material you can take your specimens to them, or send them by mail if it's too far to drive there.  Once your materials are in the hand of a professional plant taxonomist, you are connected to the network.  If your local taxonomist can't fully ID your plant, he or she can at least narrow it down to a plant family, genus or other grouping and send it off to a specialist.  Some places will charge a fee, particularly for commercial purposes, others will do it for free.  If it's a common local plant, they may be able to give you the ID instantly.

But experts frequently turn to other experts for critical identification of uncommon plant materials.  Each typically has his or her own particular genus or family that they have spent years studying, which often have specialized terminology or details that require years of training and practice to recognize.  In the grass family, for example, we have to distinguish between paleas, lemmas, glumes, and awns, and in mosses we have calyptras, peristomes, opercula, etc. In the genus Sphagnum, the distinguishing characters not only have funny names, but can only be seen in special preparations under the light microscope.

Now, if you're that panicked mother, you've already wasted valuable time reading the above paragraphs.  You should already be at the hospital!  The baseline information, and a sample of the plant material will still be very important in identifying the poison and administering the appropriate antidote.  The information here will, however, help prepare you for future incidences and to avoid poisonous materials in the future.

B. Plunging on yourself.  How do you start?

You don't have to have a PhD in plant taxonomy to begin the identification process, narrow the plant ID to a handful of possibilities, or possibly even come up with the correct scientific name for the plant. It's a challenge, but can be a very rewarding learning process.  The tools available run the gamut from pictorial guides that anyone can use, to more technical keys that require some learning and practice.  There are books and a growing list of useful websites to help with identifying plant materials of a particular type or geographic origin.

Pictorial wildflower guides, like this one for
South Africa,can be very useful, but you must
pay close attention to detail - there are many
look-alikes due to similar adaptations for
pollination. 
You can begin with non-technical field guides that contain descriptions and color photographs, usually arranged by flower color, or sometimes by habitat.  These are available for many states, national parks, or other specific regions.  These are not usually comprehensive, but contain the most common species. If you come up with a possible match, you can do a web search for images to confirm.  But beware - you can get many erroneous hits, typically of other plants that might be on the same web page as the plant you're looking for.

You can move from that beginning to more formal floras or handbooks, which contain all known species for a specific area with technical descriptions and identification keys.   An identification key takes you through a series of either-or questions that progressively narrow the field of possibilities.  A key might begin
More advanced references,
like Wunderlin and Hansen's
Guide to the plants of Florida,
require the use of technical
keys and specialized
terminology.
with "flowers red" vs "flowers yellow."  Depending on your choice, you're directed to a later subsection of the key that deals only with plants with red flowers or the one that deals only with yellow flowers.  So, if you were faced with a possible 1000 plants at the beginning of the exercise, after the first step, you could potentially be down to 500 possibilities (more or less, depending on how many red and yellow flowered plants are actually in the area).  You could get really lucky and find that there is only one red-flowered species in the area, and you have it.  Simple, right?

Well, not always.  Keys in general are notoriously difficult, even sometimes for trained taxonomists.  First, you have to learn a lot of specialized terminology. You have to know the names of all the parts of a flower, and the parts of each flower part, and there are typically special names for unique forms of flower or fruit parts found in particular families or genera.

Professional taxonomists typically reduce the time they spend with keys with various shortcuts.  The most important of these is to learn to recognize the various plant families.   Keys to the families are particularly difficult as the technical characteristics that distinguish modern plant families tend to be rather obscure.

Someday, we might be able to just "google" a plant by entering in an image for "facial recognition."   An experienced taxonomist can often recognize instantly plants that he has seen before, sometimes even just by the hue and pattern of colors in a field.  I's the sames as when you see someone you know.  You don't have to measure the length of your spouse's earlobes or the precise color of their eyes to identify them.  A taxonomist likewise, doesn't have to laboriously count ovary locules or measure the length of anthers in order to identify a plant he or she has seen before.  So a similar sort of facial recognition of plants may be possible with computers in the future.  Another tool that may eventually allow for instant identification would be some kind of DNA scanner, a Star-Trekish tricorder, if you like.

For now we still need professional taxonomists, and in fact a large number of them will be needed to program the above technology!)  This is all the more reason that it should be alarming that taxonomists are dwindling in numbers, as I pointed out in my previous post, and as eloquently pleaded by the famous Indian taxonomist R. R. Rao.