Rhynchospora caduca |
Rhynchospora knieskernii |
|
---|---|---|
anglestem beaksedge |
knieskern's beaksedge |
|
Habit | Plants perennial, cespitose, 70–150 cm; rhizomes often present, short, scaly. | Plants perennial, cespitose, to 50 cm; rhizomes absent. |
Culms | erect or ascending, leafy, trigonous. |
erect to arching, leafy, linear to filiform, nearly triangular. |
Leaves | exceeded by culm; blades linear, proximally 4–7 mm wide, apex trigonous, tapering. |
ascending, overtopped by culm; blades flat, linear to filiform, to 1.8 mm wide, apex distally involute, trigonous, setaceous. |
Inflorescences | terminal and axillary; clusters 3–6, mostly dense, narrowly to broadly turbinate, branches ascending; leafy bracts exceeeding proximalmost inflorescences. |
terminal and axillary, spikelet clusters 2–4, widely spaced, the lowest near plant base; clusters compact, broadly turbinate to hemispheric, to 1.5 cm wide; leafy bracts curved, setaceous, slightly to greatly overtopping subtended compounds. |
Spikelets | rich brown, ovoid, (3–)4–5 mm, apex acuminate; fertile scales ovate, 2.5–3.5 mm, apex acuminate, midrib included or shortexcurrent. |
dark brown, lance-ellipsoid, 2–3 mm; fertile scales 2 mm, apex acute, midrib short-excurrent or not. |
Flowers | perianth bristles mostly 6, exceeding tubercle tip. |
perianth bristles 6, ± as long as fruit body, retrorsely barbellate. |
Fruits | mostly 3–4 per spikelet, 2–2.2 mm; body brown on short pedicellar (to 0.3 mm) stalk, broadly obovoid, lenticular, 1.3–1.5 × 1–1.5 mm, surfaces transversely rugulose, vertically finely striate and rectangularalveolate; tubercle compressed, triangular acuminate, 0.5–0.8 mm, edges setulose. |
mostly 2 per spikelet, 1.5–1.9 mm; body brown with yellowish center, ellipsoid, lenticular distal to short stipe, 1–1.3 × 0.6–0.8 mm; tubercle triangular, 0.3–0.6 mm, distinctly shorter than fruit body. |
Rhynchospora caduca |
Rhynchospora knieskernii |
|
Phenology | Fruiting summer–fall. | Fruiting summer–fall. |
Habitat | Low meadows, clearings, marshes, marsh borders, seeps, bog moats, savannas, ditches, pine flatwoods, swamps | Moist to wet pine barrens, sand pits, borrow pits |
Elevation | 0–400 m (0–1300 ft) | 0–100 m (0–300 ft) |
Distribution |
AL; AR; FL; GA; LA; MS; NC; OK; SC; TN; TX; VA
|
DE; NJ |
Discussion | Rhynchospora caduca has its closest relationships with the even more robust R. odorata Grisebach, on the one hand, and the swampinhabiting, more slender, and rhizomatous R. mixta Britton ex Small, on the other. Intergrades with R. odorata appear in Alabama and northwest Florida; intergrades with R. mixta appear where ranges overlap in both the Atlantic and Gulf coastal plains. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Rhynchospora knieskernii is in the Center for Plant Conservation’s National Collection of Endangered Plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 223. | FNA vol. 23, p. 211. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Phaeocephalum caducum, R. patula | |
Name authority | Elliott: Sketch Bot. S. Carolina 1: 62. (1816) | J. Carey: Amer. J. Sci. Arts, ser. 2, 4: 25. (1847) |
Web links |