keys to the vascular plants of east texas - Botanical Research ...

RHYNCHOSPORA/CYPERACEAE
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34. Culms lax to spreading to stiffly erect, (10–)20–60(–80) cm tall; leaves
usually 1–2(–3) mm wide; branchlets of the cymes terminating in small
knobby glomerules, the bracts inconspicuous; spikelets (2–)2.5–3(–4)
mm long, roundish, brown to dark brown; fertile spikelet scales 1.7–2.3
mm long, the midrib usually not extending past tip of scale __________ R. globularis
34. Culms stiffly erect, 60–100(–120) cm tall; leaves usually 2–5 mm wide;
branchlets of the cymes usually terminating in dense glomerules, with
setaceous bracts conspicuous (giving the inflorescence a bristly appearance);
spikelets usually 3–4 mm long, elongate, reddish brown; fertile
spikelet scales 2.5–3 mm long, the midrib often extending past tip
of scale ___________________________________________________ R. recognita
31. Perianth bristles as long as the achenes or longer.
35. Tubercle margins smooth; achenes 1–1.2 mm long ______________________ R. microcarpa
35. Tubercle margins setose (= with minute bristles—use dissecting scope or
strong hand lens); achenes 1.2–1.5 mm long.
36. Achenes nearly round to broadly obovoid, the surface with horizontal ridges
(the cells oblong in outline); tubercle short deltoid; inflorescences with
spikelet clusters dense; plants without evident rhizomes or with short rhizomes
__________________________________________________________ R. caduca
36. Achenes ellipsoid to narrowly obovoid, the surface without horizontal
ridges, merely minutely honey-combed (the cells nearly round in outline);
tubercle deltoid-subulate (relatively narrower than in R. caduca); inflorescences
with spikelet clusters mostly diffuse; plants usually with welldeveloped,
often elongate rhizomes (to 10 cm or more long) ________________ R. mixta
Rhynchospora caduca Elliott, (falling early, short-lived), ANGLE-STEM BEAK SEDGE, ANGLE-STEM
BEAK-RUSH. Perennial 70–150 cm tall, often with short scaly rhizomes; inflorescences with
spikelet clusters dense; spikelets (3–)4–5 mm long; achenes 1.3–1.5 mm long, nearly round to
broadly obovoid, lenticular; tubercles 0.5–0.8 mm long, the margins with minute bristles.
Ditches, other low or moist areas; mainly se part of East TX and n Gulf Prairies and Marshes,
also Bowie Co. (BRIT) in Red River drainage and Gonzales Co. (Turner et al. 2003) near sw margin
of East TX; also e Edwards Plateau; se U.S. from VA s to FL w to OK and TX. Apr–Nov. [R.
patula A. Gray] This species intergrades with R. mixta (Kral 2002c).
Rhynchospora capitellata (Michx.) Vahl, (having a small head), BROWNISH BEAK SEDGE, POINT-
BEAK BEAK-RUSH. Tufted perennial ca. 20–100 cm tall; inflorescences with clusters of spikelets
usually borne singly or in groups of ca. 2–3; spikelets 3.5–4(–5) mm long; perianth bristles usually
with retrorse barbs (very rarely antrorse); achenes usually 1.2–1.5 mm long, obovoid, lenticular;
tubercles (0.8–)0.9–1.2(–1.6) mm long. Shorelines, boggy areas; widely scattered in East
TX; se Canada and widespread in the e 1/2 of the U.S., also CA and OR. Jul–Aug. [R. glomerata
(L.) Vahl var. capitellata (Michx.) Kük., R. glomerata var. leptocarpa Chapm. ex Britton, R.
glomerata var. minor Britton, R. leptocarpa (Chapm. ex Britton) Small] This species intergrades
with R. glomerata (Kral 2002c). Sorrie (2000) indicated that R. leptocarpa (Chapm. ex Britton)
Small (occurring from NC s to FL w to LA) should be split from R. capitellata; Kral (2002c),
however, noted that there is “a strong overlap” with R. capitellata. Rhynchospora leptocarpa was
erroneously mapped for TX by Turner et al. (2003) (see Sorrie 2000).
Rhynchospora cephalantha A. Gray, (bearing heads), BUNCHED BEAK SEDGE. Tufted perennial
0.4–1.1(–1.5) m tall; inflorescences with spikelets in dense, globose or nearly globose, widely
spaced clusters; spikelets 4–5(–6) mm long, each spikelet with only one achene; perianth
bristles usually with retrorse barbs (very rarely antrorse); achenes (1.8–)2–2.3(–2.4) mm long,
obovoid, lenticular; tubercle (1–)1.4–2.4 mm long, triangular-subulate, at least 0.5 mm wide at