For over two centuries at the least, one of the Pinewoods shaggy stars has been obscured in the Aster galaxy of systematic complexity. But our recent taxonomic big bang deconstructed that Linnaean genus, spinning off a host of distinct entities, most prominently Symphyotrichum, an asterism of nearly 100 species. But many other formations emerged, such as Eucephalus, Eurybia, and Ionactis. Among those, Oclemena is one of the lesser groupings, materializing as a minor constellation in the Asteraceous universe. Having just three points, a single one shines in our Apalachicola firmament, Oclemena reticulata. The common names, White Top Aster and Pine Barren Aster harken to its galactic past.
The Short Story, 2023
The Apalachicola Flora has a single species classified as Oclemena, the Whitetop (or Pinebarren) Aster, which had been called Aster reticulata since first described by Frederick Pursh in 1813 (his Flora americae septentrionalis…). Edward Lee Greene circumscribed the genus Oclemena in 1903, segregating two other species from Aster, but that work lay dormant for some time. In a 1995 Phytologia paper, Guy Nesom “resurrected” Greene’s genus, pulling in the Whitetop Aster as Oclemena reticulata. Flora of North America lists three Oclemena species and one hybrid. Nesom considers the genus monophyletic, and most closely aligned to Doellingeria.
The Main Story
With a single species in the Apalachicola area, identifying Oclemena can be simple, once you already “know” the plant. Attempting to assign names de novo, using floras and picture books, this may be just another white-flowered Composite, with imposters that make determination more difficult. I was confused, for example, in learning there’s a second Composite also called Whitetop Aster, Seriocarpus tortifolius. Wandering further west in the Panhandle, I discovered there’s yet another “whitetop”, Seriocarpus asteroides, the Toothed Whitetop Aster.
But Oclemena reticulata is fairly easily identified by a suite of characteristics not readily apparent in keys and technical descriptions. You are probably looking at O. reticulata if you run into a robust, erect, leafy composite that:
- sends up a few to several stiff stems from its perennial base,
- bears broad, sessile, alternating, cauline leaves that practically conceal the entire stem
- that are elliptical, with entire margins, and somewhat conduplicate (folded along the midvein like an opened book),
- gradually reduced in length from the base to top of the stem (1.5-2.5 feet tall)
- showing striking raised, reticulated veins abaxially (on the lower surface), covered in soft, white pubescence
- produces terminal spreading arrays of flower heads with about 10 white, 12 mm (½”) rays
- that are sort of twisted and casual
- surrounding a few yellow disc flowers
In less condensed prose, the plant stands out as a stiffly upright perennating herb, often with several stems ascending from the previous year’s base, topping out at less than a meter. Leaves are broadly-elliptic to oblong, somewhat conduplicate (folded along the mid vein), and appearing somewhat whitened due to the curious cover of soft, clear, broad-based trichomes that are usually geniculate (apically bent). The name “reticulata” is most appropriate, in that smaller veins show as clear reticulations on the adaxial surface, while the main vein and larger secondary veins on the lower (abaxial) surface are expressed, showing a beautifully reticulate, highly dimensional structure, made more apparent by the dense, soft pubescence. Leaf margins appear micro-serrate due to thickened hyaline trichomes.
Leaves are regularly spaced along the stem, gradually decreasing in size from 10 cm in length basally to 3 cm directly subtending the terminal inflorescence, which is an open structure that broadens somewhat over the course of development. Flowering heads mature sequentially, each head with white rays laying casually at varying angles. As Greene observed in Oclemena acuminata (see his writings below), immature flower heads are nodding, moving to an erect position as florets begin to open.
Glancing at photos of Oclemena and Seriocarpus in Hammer’s great book and in the ISB Atlas (or on the web), without a scale, flowering heads appear similar, but scale is everything. Our regional Seriocarpus tortifolius is a smaller plant with more widely-spaced, smaller, petiolate, obovate & flat leaves that are twisted and contorted such that the blades bear a varyingly vertical orientation. Oclemena is also more robust, with larger, thicker leaves and stems. But leaf texture is the clear giveaway, with the veins of Oclemena leaves raised (abaxially) and pubescent. Oclemena has yellow disc flowers, while those of Seriocarpus tortifolius are white. Moreover, Oclemena phyllaries are green, while the involucre of S. tortifolius is white, with phyllaries merely tipped in green. The inflorescence of Oclemena is much larger and more open as contrasted with that of S. tortifolius. I’ve included an image comparing the two plants, with Oclemena to the right of the Seriocarpus tortifolius.
Another plant that appeared similar to me, until I was able to give it a closer look, is the completely unrelated Eupatorium rotundifolium. I know anyone familiar with Composites will turn their heads, but for someone unfamiliar with these plants, it’s instructive to note the differences – which are many. The similarity is that both plants produce stiff, erect stems, that can be 2-3 feet tall, evenly outfitted with broad, sessile, cauline leaves to the point that each stem terminates with a spreading white inflorescence. The leaves of both plants show reticulate venation abaxially, but the two are easily differentiated. (See photos below). The Eupatorium has opposite, broadly ovate leaves that spread out, showing wide spacing along the stem. The spreading inflorescence produces smaller heads that have no ray flowers; Eupatoriums produce disc flowers only.
The Inside Story
Using keys in determining Oclemena can be challenging. There are simply too many places to get lost. In the 1985 (older but easier to use) Clewell treatment, Oclemena and Seriocarpus are included as species of Aster, as was traditional prior to cladistics and molecular taxonomies. Wunderlin & Hansen (2011) recognize the genera separately. Summarizing features that are used in dichotomous keys to distinguish Oclemena, we learn these are:
- Caulescent herbs with 2-many heads,
- with Elliptical leaves that are apically broadly acute, evenly distributed along stem, gradually reduced in size, and characterized by obvious reticulate venation,
- producing Radiate heads (white rays & yellow discs) with phyllaries that are sub-equal, pale green, covered with soft hyaline hairs.
- having Pappi of capillary bristles said to be double (FNA says triple), which is imperceptible to me in fresh material. ( The pappus is, however, incredibly evident, protruding from the involucre, equally long on disc and ray flowers.)
Technical descriptions are diagnostic, but do not construct the gestalt useful for lay naturalists. Here’s the entry for Oclemena reticulata from the Flora of North America (FNA) website (May 2023):
“Plants 30–90 cm (cespitose or densely clonal; caudices superficial, woody, branched, and deep, rhizomes short to long, herbaceous or woody). Stems 1–4+, erect, stout (2–4 mm diam.), straight, simple, densely villosulous, ± glandular distally. Leaves 12–30, regularly distributed, proximal sometimes withering by flowering; sessile to short-petiolate (petioles 1–2 mm); blades obovate-elliptic or ovate-elliptic to elliptic-oblong, 25–110 × 10–40 mm, bases cuneate to rounded, margins revolute, ± undulate, entire or serrate distally, teeth coarse, ± obtuse, apices acute to obtuse, mucronate, faces densely villosulo-puberulent, stipitate-glandular, adaxial more so, array leaves reduced distally. Heads (3–)9–40(–67) in corymbiform arrays, branches strongly ascending, at acute angles with stems. Peduncles stout, 2–5 cm, ± densely villosulous, stipitate-glandular. Involucres 4.8–7.2 mm. Phyllaries lance-ovate (outer) to lance-linear (inner), ± pilose, gland-dotted; bracts 0–1(–2), linear, villosulous-puberulent. Ray florets (5–)7–11(–14); corollas white to pinkish, (10–)11.5–17(–19) × (0.8–)1–1.8(–2.2) mm. Disc florets (10–)15–30(–35); corollas slightly ampliate, 5–8 mm, sparsely glandular; tubes longer than narrowly campanulate throats, strigillose, lobes slightly spreading, lanceolate, 2–4 mm. Cypselae tan, fusiform, ± compressed, (1.5–)2–4.2 mm, ribs 6–8 (lighter than bodies), faces strigillose, gland-dotted; pappi of whitish bristles in 3 series, ± equal to disc corollas (innermost ± clavate). 2n = 18.
Flowering spring(–summer in damaged plants). Moist (at least seasonally) sandy places, bogs, wet pine flatwoods, cypress pond margins, roadside cuts, burns; 0–50 m; Ala., Fla., Ga., S.C.
Oclemena reticulata is a southern Atlantic coastal plain element and is a facultative wetland indicator. Although most often grouped with Doellingeria, its distinctness can be perceived in the morphometric study by J. C. Semple et al. (1991), who provided a full synonymy for the species.”
The Back Story
I believe its’ worth mentioning that Oclemena is an Etymological Mystery Having learned the name is of “unknown origin”, I did my own bit of web searching. Turns out Oclemena is not a word that’s used in realms other than botany (and one steamship). I decided to see if AI could help, and addressed the following question to Chat GPT: “What do you know about Oclemena?” The response was:
“I’m sorry, but I couldn’t find any information on “Oclemena” in my existing knowledge base. It’s possible that Oclemena is a relatively unknown term or a specific reference that is not widely recognized. If Oclemena refers to something specific, please provide more context or clarify your question, and I’ll do my best to assist you.”
I haven’t been able to determine the etymology of Greene’s genus Oclemena. Searching for clues, I read comments Greene related in establishing the genus (page 4, Edward L. Greene, Leaflets of Botanical Observation and Criticism, 1903, Vol 1.), and include them here:
“Further Segregates from Aster – Somewhat late in summer seven years ago, following an old wood road up a mountain side in northern Pennsylvania, I paused for a moment in admiration of some nodding corymbs that in partial shade were peering a little above the rest of the woodland herbage and seems as if they must be those of some asteraceous plant; though up to that time I had not seen, or even heard of any asteraceous plant with nodding heads. But on a near approach to the plants I discovered by the unmistakable cut of the foliage that this was what I had known well enough in herbarium specimens for perhaps forty years, what is called Aster acuminatus. Somewhat later that season I transferred roots of the plant to my garden near Washington, discovering what also had not, and not until now been understood, that the species propagates by tubers rather by stolen. At the end of each long slender subterraneous branch a small (regan?) is formed which, exactly resembles a small potato, and from each of these springs a plant for the next year.
Having studied this type in the living state for another season, I in 1897 labelled all my herbarium sheets of this species Oclemena acuminata, having first noted that neither the achenes nor the pappus are those of the genus Aster, the former being prismatic rather than compressed, and the later much too fine and soft. As a genus, Oclemena bears much the same relation to Aster which Erechtites bears to Senecio.
I am also now persuaded that the genus is not monotypic, and would name as a second species O. nemoralis, this being of course the Aster nemoralis Aiton, which, seeing it was no Aster, I formerly transferred to Eucephalus where it was not well at home. It has the same habit, and the same reproduction by tubers which the type species portrays, though its pappus is firmer, and its achenes, though 3-angled are a little compressed. Whether its heads are nodding before expansion or erect I do not know, never yet having had the fortune of seeing the plant alive. That in the type species the heads are nodding before expansion has now at last been announced by Mr. Small in his new book already famous.”
It appears there’s no ready explanation for the name; Oclemena doesn’t seem based on Latin or Greek roots, at least nothing I’ve discovered. Hammer, in his 2018 Complete Guide to Florida Wildflowers mentions the 1897 sinking of a New York steamship named OCLEMENA, suggesting this could have inspired the generic name. That makes sense when you read Greene’s 1903 description, where he specifically mentions 1897 as the year he first penned the name.
And there are tantalizing clues. Greene first noted unique attributes of the plant in a northern Pennsylvania woodland. The steamship OCLEMENA operated as an excursion vessel out of Sodus Point*, (Lake Ontario) which was noted as a shipping depot for Pennsylvania coal. Querying the Maritime History of the Great Lakes website, one finds several reports. From Jun 1896 we learn: “The pleasure boat OCLEMENA, owned by George S. Wright and S.S. Granger of this city was sold yesterday to John Hanan of Ogdensburg. The OCLEMENA has been in commission on Lake Ontario for some time. The price received for her could not be learned. Buffalo Morning Express, June 25, 1896 3-1” An October 1897 record that reports its “grounding” indicates: “Steam screw OCLEMENA. U.S. No. 155182. Of 149.52 tons gross; 109.97 tons net. Built Buffalo N.Y. 1890. Home port, Ogdensburg, N.Y. 93.7 x 18.0 x 7.2” Curiously, the only anagram one can construct using all letters in Oclemena is Coalmen…. I contacted the Archivist at Thunder Bay, asking where I might look to learn more about this ship, specifically why it was named OCLEMENA. Perhaps someone who discovers this passage will have a missing piece of this puzzle.
*See also notes on William E. Bradley, in J. B. Mansfield, History of the Great Lakes, Vol1. “In 1892 he was appointed chief engineer of the excursion Oclemena of Sodus Point”