Rhynchospora latifolia |
Rhynchospora mixta |
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sandswamp whitetop |
mingled beaksedge |
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Habit | Plants perennial, cespitose or solitary, to 100 cm; rhizomes scaly, 3–4 mm thick. | Plants perennial, cespitose, 80–100 cm; rhizomes stoloniferous, often elongate, slender, to 1 dm or more. |
Culms | arching or erect, leafy-based, distally wandlike, terete, multiribbed. |
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Leaves | ascending to spreading, overtopped by scape; blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous. |
exceeded by culm; blades lax, linear, proximally flat, 3–5 mm wide, apex abruptly narrowed, trigonous, subulate. |
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. |
spikelet clusters 4–6, mostly widely spaced; peduncles erect or ascending, slender; branches capillary, divaricate, or widely spreading, to small clusters of 1–few spikelets; leafy bracts mostly exceeding clusters. |
Spikelets | white, ovoid, 5–7 mm; fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute. |
lanceovoid, 3–4(–6) mm, apex acute to acuminate; fertile scales elliptic, 2.5 mm, apex acute, midrib forming mucro or awn. |
Flowers | perianth absent. |
perianth bristles 6, overtopping tubercle, antrorsely barbellate. |
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. |
mostly 2–4(–several) per spikelet, (1.5–)1.8–2(–2.1); body greenish or pale brown, broadly ellipsoid to narrowly obovoid, lenticular, 1.2–1.5 × 1–1.2 mm; surfaces transversely finely wavy-rugulose, intervals vertically striatealveolate, or alveolae isodiametric; tubercle flat, triangular-subulate, 0.5–0.6(–0.8) mm. |
2n | = 12. |
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Rhynchospora latifolia |
Rhynchospora mixta |
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Phenology | Fruiting late spring–summer. | Fruiting summer–fall. |
Habitat | Sands and peats of bogs in pine savannas and flatwoods | Sandy silts of swamp forests and environs |
Elevation | 0–200 m (0–700 ft) | 0–200 m (0–700 ft) |
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX
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AL; FL; GA; LA; MS; NC; SC; TX
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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.) |
Some extremes of Rhynchospora caduca with more diffuse inflorescences are mistaken for R. mixta, particularly those in which ultimate inflorescence branches lead to solitary spikelets. In those rare instances one should find a somewhat larger spikelet and a broader fruit than is typical for R. mixta. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23. | FNA vol. 23, p. 224. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Dichromena latifolia, R. stellata var. latifolia | Phaeocephalum proliferum, R. prolifera |
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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