Rhynchospora latifolia |
Rhynchospora perplexa |
|
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sandswamp whitetop |
pineland beaksedge |
|
Habit | Plants perennial, cespitose or solitary, to 100 cm; rhizomes scaly, 3–4 mm thick. | Plants perennial, cespitose, 50–110 cm; rhizomes absent. |
Culms | arching or erect, leafy-based, distally wandlike, terete, multiribbed. |
lax, often excurved, slender, ± terete or trigonous. |
Leaves | ascending to spreading, overtopped by scape; blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous. |
ascending, exceeded by culm; blades linear, proximally flat, 1.5–2.5 mm wide, apex trigonous, subulate, tapering. |
Inflorescences | terminal, headlike clusters of spikelets, clusters dense, leafy-involucrate; involucral bracts several, spreading to downcurved, longest 6–13 cm × 5–10 mm, mostly white to midbract, then green, abruptly narrowly linear. |
clusters 3–4, widely spaced, narrowly, compactly, or diffusely turbinate; leafy bracts exceeding proximal clusters. |
Spikelets | white, ovoid, 5–7 mm; fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute. |
deep redbrown, ovoid to broadly ellipsoid, 2–3 mm, apex acute to acuminate; fertile scales broadly elliptic to obovate or orbiculate, 1.4–2(–2.5) mm, apex rounded to notched, midrib shortexcurrent. |
Flowers | perianth absent. |
perianth bristles 0–3, vestigial when present. |
Fruits | several per spikelet, 1.5–2 mm; body yellowish to deep brown, tumidly lenticular, broadly obovoid to orbicular or oblate, 1.5 mm, widest at or toward midbody, margins flowing to tubercle; surfaces with many fine rows of vertical shallow lattices, their contiguous ends making transverse rows of papillae; tubercle crescent-based, depressed-triangular, 0.5 mm, apex acute. |
2–4 per spikelet, 1.5 mm; body pale brown to brown, strongly flattened, orbicular to broadly obovoid, 1–1.3 × 0.9–1.2 mm, surfaces sharply transversely wavyrugose, intervals finely vertically striate with rows of linearrectangular alveolae; tubercle depressed, triangular, flattened, 0.2–0.3 mm, base lunate. |
2n | = 12. |
|
Rhynchospora latifolia |
Rhynchospora perplexa |
|
Phenology | Fruiting late spring–summer. | Fruiting late spring–fall or all year (south). |
Habitat | Sands and peats of bogs in pine savannas and flatwoods | Sands and peats of pond and lakeshores, depressions in savannas and flatwoods, or seeps |
Elevation | 0–200 m (0–700 ft) | 0–400 m (0–1300 ft) |
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX
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AL; FL; GA; LA; MS; NC; SC; TN; TX; VA; Central America; West Indies (Cuba, Dominican Republic) |
Discussion | A specimen collected near Tullahoma, Tennessee, reported as Dichromena latifolia (A. Gattinger 1901), was later destroyed by fire. I did not see the specimen, nor was a description of it published. Because extant populations of the similar Rhynchospora colorata are just over the border in Alabama, that species is likely to have been the one found by Gattinger. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
In habit and in shape, size, and color of spikelet, Rhynchospora perplexa strongly resembles R. microcarpa, a species with which it is commonly associated in the Coastal Plain. An examination of the fruit shows those of R. perplexa to be flattened, with fewer and much coarser transverse ridges, the intervals with very narrow vertical alveolae. The perianth in most instances is absent or rudimentary. Fruit of R. microcarpa is biconvex with more transverse ridges (eight or more), the intervals more coarsely alveolate; its perianth bristles are six, evident, extending at least halfway up the fruit body. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23. | FNA vol. 23, p. 229. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Dichromena latifolia, R. stellata var. latifolia | Phaeocephalum perplexum |
Name authority | (Baldwin) W. W. Thomas: Mem. New York Bot. Gard. 37: 86. (1984) | Britton: in J. K. Small, Fl. S.E. U.S., 197, 1328. (1903) |
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