Language is the basis for modern civilization. Plenty of animals communicate without the literacy available through written records, but human endeavors depend on words, words that can be broadcast, exchanged, challenged, and archived. There’re such moving targets as street talk, formal presentation, poetry and prose, as well as dialects and slang, in practically every living language. And any task or specialty requires proficiency in a working terminology. Sciences are beasts in this regard, botany being no exception.
Before diving into botanical terminology, I decided to check in with society’s word merchants, the poets, scholars, linguists, and philosophers. The following slides surface some thoughts from those realms.
From childhood to the extremes of professionalism, we are admonished to:
As botanists and naturalists, ours are many, often arcane.
Born in the medical arts of pharmacognosy and the applied endeavors of agriculture, contemporary plant science is a Western study, expressed and advanced historically in European and Mediterranean languages – Latin being core. Even as vernacular languages came to predominate, for three centuriesWestern scientists published the major works in Latin. And only recently did Botanists vote to drop the long-standing requirement that description of a new species must be Latinized. These are among the many reasons botanical terminology leans heavily to Latin (and Greek). As wearisome as those terms might seem, a side benefit is their freedom from street currency.
Yes, Botanical terminology expands and meanings shift, but a botanist in 2025, reading a plant text or description from 1850 is likely to take the same understanding as the original author intended. Our Latin-based terms will shift and take on new freight, but they are buffered from everyday usage, which means more vernacular words, like family, leaf, flower, and fruit can prove problematic. In the same breath, a botanist might speak of her family and friends while discussing aspects of the Mint family. Almost any person will know the words leaf, flower, and fruit, but would likely be surprised to learn that in botanical fields, those are strictly defined terms. The same would be true for most specialties – the more technical the endeavor, the more precise the language required. As a point of trivia, the study of technical terminologies has been called “Glossology.”
There certainly are many ways to categorize botanical terms, My own thoughts are presented in the following slide. There’s taxonomic usage, which is by convention Latinized. Binomials and the various systematic categories are exercises in terminology, attempts to name and pigeon-hole plants with precision. Then I think of analytical terminologies, from the many mathematical and chemical formulations and methods to the language of experimental science and genetic research, to the more recently surfaced cladistic and evolutionary categories that one must internalize in order to appreciate today’s research. I segregate Topical and Organizational terminologies because different realms of inquiry and work have adopted their own “ologies”, and each field has its kinds of reports as well as language practices for discussion and publication. In this presentation, I’m sidestepping those areas.
For the current discussion, we focus on the gamut of terms used in descriptive botany; how do we circumscribe words to substitute for images? How do we fix and share the meanings of words such that comparisons can be made based on sometimes-subtle features?
The slide below illustrates the first page of keys in the 3rd edition of the Guide to the Vascular Plants of Florida, Wunderlin and Hansen (2011). I highlighted terms one would need to understand in order to operate this key: heads, ligule, corolla, radiate, pappus, capillary, plumose, bristles, pluose, achene, thyrsiform, paniculate, etc…. Lacking some immersion in botanical glossology, the information bound up in this concise key is a mystery. Yes, the Guide includes a glossary in which you can search each unfamiliar term, but good luck. A “head” is defined as a “tight cluster of sessile or subsessile flowers.” Basically, to explore botanical literature, people need a good basic internal lexicon of botanical terminology. That’s not as daunting as it seems. Terminologies evolved from roots and usage that give clues to their meanings.
One place to start is with the ways botanists describe and differentiate plants. Formally, a “description” is a complete accounting of characters and features, from the physical to the physiological and ecological. A “diagnosis” is a clear statement as to what distinguishes a plant, especially as compared to other similar forms. It’s the diagnostic aspects that are useful in keys. In the slide below I’ve summarized the most common attributes botanists use in descriptions and diagnoses.
For the Naturalist, out in the field, it really boils down to what we can see, feel, taste, and smell. What is the substance of a leaf, thin and papery or thickened and leathery? What’s the surface texture? Is it smooth? Chalky? Pubescent? How do you gauge and compare textural differences? (I find that touching a leaf to the bottom of my lip gives more information than is available using my fingers.)
What’s the basis for color comparisons? Does the author use one of several color charts available (such as the RHS system)?
How does the author employ terms for shapes? Are proportions and dimensions given? Are origin (insertion, i.e. point of attachment) and architecture described?
These are features useful in field studies. But they are all based on a simple understanding of plant parts. As was described in the Ten Big Ideas webinar, plants only make Roots, Stems, and Leaves (and Flowers/Fruit as modified Leaves). Descriptive terms are based on features of those parts, and usually presented in the same sequence.
The basic problem with roots is that most people don’t inspect the underground aspects of plants. And herbarium specimens frequently do not voucher or make mention of root or underground stem structure. Moreover, roots do not show a lot of surface structure, at least to the naked eye. In the slide below, note the most discussed underground structures – Tiller, Rhizomes, Corms, and Bulbs – are stems (anatomically).
Distinguishing between roots and stems can be confusing for a general audience. At the simplest level, underground stems produce growth buds (which can produce more stem tissue) regularly, at nodes. Note rhizomes are usually defined as underground, like Tillers, but some stems (especially fleshy, storage stems) that grow closely to the ground surface are termed rhizomes, such as those of Iris and Banana. Stems skipping along the surface will be called Stolons or Runners – as with Strawberries and many Grasses.
The two slides below showcase field studies by Steve Orzell and his colleagues, documenting work published in 2024 that involves nearly 200 species of fire-adapted orest floor plants native to Florida’s Pine Flatwoods. To appreciate the information presented, you’ll need to have a well-developed internal botanical lexicon. Some terms employed in the paragraph shown: 1. “matrix graminoids” – the base palatte of grasses that carpet the forest floor, not as a lawn, but in tightly-spaced tufts; 2. “epigeogenous” and “hypogeogenous” rhizomes – stems that run atop (epi) or under (hypo) the ground surface; 3. “acaulescent” – in the case of the palm, not forming an erect stem; 4. “caulescent” – plants that bear leaves along their above ground, vertical stems; 5. “geoxylic suffrutex” – a low shrub (suffrutex) with a woody subterranean base (geo – earth; xyl – xylem, wood); 6. “cespitose graminoids” – tuft-forming grasses with tightly-clustered stems that hang out close to the ground surface.
The slide below illustrates three perennials: 1. Phoebanthus, a virgate (wandlike) Composite with cauline (along the stem), alternating leaves, and a thickened underground rhizome; 2. Rhexia alifanus, a Melastome with opposite cauline leaves and a large, woody underground stem (a geoxyle) that allows the plant to resprount quickly following fire; and 3. two species of Aletris, acaulescent rosulate (leaves in a basal rosette arising from a thick epigeogenous rhizomatous stem) herbs with fleshy fibrous root systems. Each plant, therefore, produces two very different stems.
Stems in the slide below, remind us of attachment and surface textural terminology. The two Pityopsis (with alternate, non-petiolate leaves) speak to short, scurfy to stipitate glandular trichomes in P. aspera and long, appressed silky (thus “sericious”) pubescence on P. graminifolia. In the pair below we see Chryopsis, with long, spreading (standing out from the stem) silky hairs aside the opposite-leaved Hypericum setosum, the name of which reminds us this is among the few Hypericums to be noticeably pubescent. The epithet “setose” implies bristly hairs, but the Flora describes the plant as being “scabrose-tomentose to pilose”. I’m not sure there’s much difference in those terms, but each author differs a bit in how texture is described. The pair of photos to the right shows two plants with “decurrent” tissue, interpreted as leaf blade that runs along the stem. The Rhexia has opposite leaves while the Pterocaulon (with alternate leaves) shows significant textural distinction between the adaxial (green), upper leaf surface and the abaxial (lower), lanate (wooly white) surface. Note the decurrent tissue along the stem carries that same textural distinction between upper and lower leaf area.
Images below (as well as definitions of many terms) are borrowed from a well-worn copy of the very useful resource guide, Vascular Plant Systematics, published by Radford et al (1974). The illustrations remind us that stems establish above-ground (thus generally visible) plant architecture. It is this structure that sets the pattern for plant habit and ecological habitats. Unsurprisingly, there are many structural types that do not conform to common conceptions as to what makes a stem, because a stem is defined by its internal anatomy and patterns of growth as much as by outward appearance. Thus a Thorn is defined as stem tissue (often formed by an axillary bud) that is pointed, woody, and wicked, as compared to pointed leaves we call Spines and sharp productions from the bark that we call Prickles. As discussed for the Grass family, the sharp projections of Sandspurs are reduced spiny bracts that encase fruiting spikelets, making sandspurs (sandburrs), technically, spiny.
Arrangement of buds and leaves at nodes along stems (“laid down” by the stem growing tip, i.e. the SAM, the Shoot Apical Meristem) is the basis for vegetative cover and branching patterns, all of which are characteristic to each given plant species. The study of leaf arrangement is called “phyllotaxy,” and determination as to whether leaves are consistently opposite versus alternate (in different rankings) proves remarkably useful in determining plant ID.
Which brings us to leaves. The slide below compares a stem and leaves of Oclemena reticulara to those of Eupatorium rotundifolium. Note the Oclemena leaves alternate along the stem, while those of the Eupatorium are opposite (sometimes becoming alternate just below the inflorescence). Leaves of both plants show solidly pubescent abaxial surfaces, the reticulate veins expressed, embossed, i.e. superficially raised. Leaf blades of Oclemena are elliptic to elliptic-obovate, while those of the Eupatorium could be described as ovate to triangular. The Eupatorium leaf base is rounded, as is the apex, while the Eupatorium leaf is basically truncate, while the apex is acute. The Oclemena leaf margins are entire and somewhat revolute, while those of the Eupatorium are irregularly crenate.
For the following slide sequence, we compare actual leaf shapes to those ideal patterns (which are graphic standards). I would peg Cyrilla leaves as elliptic to narrowly obovate, while Cliftonia seem obovate to obtrullate. Clethra leaves range from broadly elliptic to broadly obovate, while leaves of Itea seem widely elliptic to somewhat obovate. They are all petiolate, though Cliftonia varies to nearly sessile. Examine the leaf bases and apices to come up with your way to describe them. You’ll find a guide to base and apex descriptions a few slides down.
Note the shape of compound leaves is expressed as the outline that surrounds the entire leaf, with separate descriptors for the leaflet shapes. The Strophostyles (top rigy) takes a triangular shape, while the Ptelea compound leaf (center) is very broadly ovate and the pinnately-compound Chamaecrista (bottom right) leaf is practically oblong.
I’ve come to think of Eupatorium as the Mockingbird of Composites. Eupatorium mikanoides is so named because its distinctly petiolate triangular leaves are similar to those of the vining Mikania, while Eupatorium rotundifolium shows sessile, broadly ovate leaves and Eupatorium perfoliatum combines the bases of opposite leaves at each node to make for a “perfoliate” pattern. To the right, we see Helianthus heterophyllus, so appropriately named for the extreme variation between basal and cauline leaves in a single plant, as well as the variation between different individuals.
As we began to see above, bases, tips, and margins are subject to description as fully as stems, with the proviso being that no term could ever perfectly represent the variation within a single leaf or plant, much less between differing individuals in scattered populations (and under variable environmental conditions.) And even then, each botanist, though relying on a shared lexicon, will have a slightly different take on how to capture the essence of a character such that readers will be able to make comparisons. Indeed, it is a goal that at some level a good description may substitute for actual specimens or illustrations – all in the mind’s eye.
To my mind, the Stillingia aquatica leaf, pictured above, is a good example of serrate margins. The Viola primulifolia leaf margin is better described as crenate than serrate or dentate, in that the somewhat irregular toothing is well-rounded. Dentate requires the tiniest bit of spininess from the tip of an associated vein, while serrate really wants to conjure the image of a fine saw blade. Though taxonomists may disagree along fine points, the saving grace is that a botanist is generally consistent in judgement, so the reader becomes accustomed to the way a given specialist describes plants.
The slide below shows an unusual violet (Left image) from the Panhandle, one in which the leaves vary from typically cordate to variably lobed. A cordate leaf is pictured in the succeeding slide, showing an irregularly, coarsely dentate margin in early season leaves gives way to a somewhat palmate pattern of lobing as newer leaves are produced. To the right, however, we have a leaf of Cnidoscolos, which though a “simple” widely depressed-ovate blade, is deeply 3-lobed, the margins being so regular that some might summons the word incised to draw a better image.
People describing leaf surface texture can call on a wide offering of descriptive terms. The Flora describes Chaptalia leaves as abaxially “densely tomentose” while the upper (adaxial) surface is termed glabrate. I’m guessing this is because most floras are based on herbarium specimens. Reviewing specimen photographs, the “glabrate” description makes sense. Most mounted specimens show plants that retain the lower leaf hairs, but have lost the bulk of hairs on the upper surfaces. Field biologists will know this is something of an “artifact” – a condition affected by collecting, processing, and time. Through much of the year, fresh Chaptalia leaves are nearly white with hairs, which rub off easily (glabrate suggests this condition, hairs lost with maturity), exposing a glossy, dark green upper surface. Spotting plants in the field, however, is simplified by the fact that fresh specimens often retain a nearly-complete cover of white, spreading trichomes. I’d consider the term lanate (wooly) for the lower surface, and covered with long appressed trichomes for the upper.
To the bottom right I’ve re-posted the photograph of the nearly circular leaf of Rhynchosia because this is a picture-perfect example of rugose texture, a corrugated surface in which the veins are sunken and the lamina shows a reticulate raised patterning.
The several slides that follow showcase our native Helianthus, using herbarium specimens. Note the range of leaf shapes – Linear, thickend leaves of Helianthus carnosus as contrasted with triangular (deltoid) , distinctly petiolate leaf blades for Helianthus debilis. Check out the sessile, triangular leaves of Helianthus divaricatus (with their attenuate apices) as contrasted with the nearly petiolate, oblong, nearly blunt-tipped and glaucous leaves of H. floridanus. Then compare the glabrous (smooth, lacking hairs), leathery leaves of Helianthus floridanus to the tough, hispid texture of Helianthus heterophyllus leaves and stems.
Below we have Helianthus microcephalus, with cleanly petiolate, broad, nearly trullate blades, strongly dentate cauline margins, to the ovate leaves of Helianthus occidentalis in which leaf blade is decurrent along the petiole, tapering to the point of attachment.
Below we see Helianthus radula, a plant of unmistakable identity in situ, but a bit less distinct in its pressed and dried state Still there’s no issue in distinguishing H. radula from other Helianthus species; indeed the difficult task for the novice is imagining this is a Helianthus at all.
The last images present two specimens of Helianthus strumosus, a plant at the Southern end of its North American range in several Panhandle counties. The specimen to the left was collected by Andre Clewell at Tall Timbers, and shipped to Wunderlin for identification. The one to the right was collected in Leon County by Robert Godfrey, also sent to Wunderlin, who annotated both plants. Note the conspicuous glaucous (whitened by a waxy coating), which, curiously, is not used as a character in the key to Helianthus species.
I find it easier to recall a plant name when I know something about the name’s origin or meaning, so I searched the internet for “strumosus”, and gained a real lesson in problems encountered with the new AI search tools. The last two slides show two somewhat different stories that led me on a wild goose chase. The first told me the term is associated with scrofula, a human disease, and led me to wonder if this plant was thought to be medicinal (thus the name). Consulting the original publications before and up to Linnaeus, I could find nothing. The incredible book by Bigelow on American Medicinal Botany doesn’t include any Helianthus. Rephrasing my question, I arrived at a different AI answer, which caused me to check out Wunderlin’s treatment of Helianthus in the Flora. There I learned the name suggests a swelling at the base of the stem, though no such feature is included in the either the Flora description or in the FNA (Flora of North America) treatment. Let me know if you know..
We come to flowers, but will just skim over this terminology, since much of past presentations focused on floral characteristics, and the final webinar will also delve into terminology associated with flowers. Here I simple give an overview of flower form, which varies from types of flowers considered more ancient to those in which parts are variously united, even reduced. On one hand, that encompases flowers with separate parts (sepals and petals free from each other, stamens separate, neither married to one another nor to other flower parts, and even separate pistils, like those of Magnolia, Clematis, and Rose. In another direction we encounter the tubular flowers, the Morning Glories, Mints, and Asters, while in other lineages we discover those plants with highly reduced and modified floral parts, such as Grasses and Sedges.
Though not simply categorized, we discover there are several basic floral forms that play out in various plant groups, recognizable forms that can be variously grouped. One way to categorize flowers is by regarding their symmetry. The white Pineland Gentian and the Nothoscordon in the left of the photo below show radial symmetry, termed actinomorphic, while the Lonicera is more bilaterally symmetrical (zygomorphic). That doesn’t always pan out, but another set of categories, mentioned above, analyzes flowers based on degree to which various parts are fused i.e. grown together., as in the red Lonicera pictured below.
Some general types are illustrated in the slide below. Artist Lizzie Harper gave me free access to her cheerful 2019 illustration various forms. On the right, Asa Gray’s 1897 Lessons in Botany shows a few of the most basic, funnelform, salverform, rotate (actinomorphic), campanulate, and labiate. We will return to floral characters next month.
In the meantime, using one of our common wildflowers, I’d like to conclude our discussion of terminology with an example of how plant definition, naming, and description depend on that shared botanical lexicon. The first slide introduces the genus Linnaeus accepted as Polygala, a genus comprising twenty-two species in his 1753 1st edition of Species Plantarum. Over the nearly 3 centuries that have passed since that printing, hundreds more species have been discovered and described, from many areas of the world. Unsurprisingly, botanists have broken up that old gang of mine; the slide lists the several genera in which Linnaeus’s original species are now categorized. Our native Florida plants are now assigned to Asemeia and Senega.
For this exercise, I’m focusing on one of our more common and easily identified plants, the Orange Milkwort, a plant we’ve called Polygala lutea since Linnaeus assigned that specific epithet in 1753.
In the series of slides below, I’ve copied the species description from Flora of North America, altering the nomenclature to accept recognition of our plants as Senega. That assignment was documented in an article published by José Pastore, Agustina Martinez, Richard Abbott, and Kurt Niebig in 2023. With kind permission from Richard Abbott I’ve had access to a digital copy of the paper and will cover some of their reasoning, while also exploring the terminology and typical format of a formal plant description.
Studies sampling among the hundreds of species that have been considered Polygala support the idea that any North America’s plants should be recognized in that separate genus, Senaga. Following up on Senega, we learn this genus is typified by a plant Linnaeus described as Polygala senega, a plant reported in the early 18th century as having been used by the Seneca Natives as a cure for snakebites. Indeed, in 1749 Linnaeus and his student Jonas Kiernander published Kiernander’s Dissertation on Radix Senega, following up on a 1742 report by Philadelphia physician John Tennent that documented the story. In 1838, French botanist Édouard Spach published the segregate genus Senega, rechristening Linnaeus’s species as Senega officianalis.
Spach’s genus was then resurrected by the work of Pastore and team, establishing several distinctions between the two groups as seen in the slide below. We learn the small flowers show great detail. Each flower has 5 sepals, 3 modest outer sepals and 2 large inner sepals that are called wings. Inside the sepals, each flower has 3 petals, two that are somewhat normal and strap-shaped, lying close to a third petal. This petal shown in the micrograph below, has a narrow base (the claw) that expands to a small platform of a petal called the keel. The keel is crested. In Polygala, the crest is a single tuft of fringes, while plants of Senega have a lobed keel bearing a fringes along the margin of each lobe. Inside the petals we find 8 stamens and a single pistil. In both Polygala and Senega, the pistil terminates in a narrow style bearing an expanded stigma. Consistently, the structure of Polygala stigmas varies from that of Senega flowers. All of this structure is quite miniature, contained within a few millimeters.
This brings us back to the description of Senega lutea. Note the sequence in which description proceeds. That isn’t whimsical; descriptions are formulaic. Here’s the normal sequence in which a plant is described. Flora of North America publishes a protocol for its authors. Theirs is fairly typical.
Back to a live specimen of Senega lutea.
Authors address the plant habit first. Our plant is considered a short-lived biennial or perennial herb. Description begins with roots and works its way up the stem.
Leaves are described in a given order, beginning with their overall size, attachment, and shape, followed by a statement as to shape, base, apex, and texture. Note the blades are described as obovate to spatulate basally, becoming more narrow, even linear further up the stem. The surfaces are smooth, i.e. glabrous.
Following roots, stems, and leaves, the overall inflorescence is described. This is termed a capitate raceme, which tells us the flowers are tightly clustered along an axis (the peduncle) that varies from 3 to 10 cm in length. Each flower has a short winged pedicel (stalk), less than 3 mm long.
Flower description begins with color, then moves from sepals to petals, to stamens and pistil. Note the sepals are “decurrent” on the supporting pedicel, which is the reason the pedicels are described as winged. The smaller sepals are ovate, from 1-2 mm log, with tiny cilia along the tips. The larger inner sepals (the wings) are elliptic, but abruptly cuspidate (with a tiny point or tail) at the apex.
After pollination, the petals are shed, but the two wings persist and remain colorful during maturation of the pistil. Each pistil bears one to two small seed that retain a fleshy external aril. The plant has a 2n chromosome number of 64 or 68.
The plants flower much of the year, living in moist to wet open areas over much of Florida.
Link to this Page: https://botanyincontext.com/bountiful-jargon/