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

RHYNCHOSPORA/CYPERACEAE
623
10. Perianth bristles variously smooth, with minute lateral barbs, or absent; tubercles
variously shaped and of various lengths.
12. Perianth bristles numerous (16–20), longer than the achenes ___________________ R. macra
12. Perianth bristles 12 or fewer, longer or shorter than the achenes or absent.
13. Perianth bristles usually with retrorse (= backward or downward, as on a
fishing hook) barbs.
14. Spikelets usually in dense globose or nearly globose clusters, the lower
spikelets usually reflexed; achenes (1.8–)2–2.3(–2.4) mm long _______ R. cephalantha
14. Spikelets usually in loose, turbinate (= top-shaped, inversely conical) or
hemispheric clusters, the lower spikelets usually ascending or spreading
(rarely reflexed); achenes 1.2–2 mm long.
15. Each spikelet with only 1 achene; tubercle narrowly triangular-subulate,
< 0.5 mm wide at base ____________________________ R. chalarocephala
15. Each spikelet usually with 2–3 achenes (if one-fruited, then an additional
rudimentary floret also present); tubercle triangular-subulate,
> 0.5 mm wide at base.
16. Achenes 1.5–2 mm long, the faces with a raised, central, pale
bulge or hump; clusters of spikelets (spikelets several–many per
cluster) in inflorescence usually borne in groups of more
than 3; spikelets 4.5–6.5 mm long ________________________ R. glomerata
16. Achenes usually 1.2–1.5 mm long, the faces without a raised,
central, bulge or hump, � uniformly brown; clusters of spikelets
in inflorescence borne singly or in groups of ca. 2–3; spikelets
3.5–4(–5) mm long ________________________________ R. capitellata
13. Perianth bristles with antrorse (= forward or upward) barbs or smooth (without
barbs) OR perianth bristles absent.
17. Surface of achenes smooth, without any ridges, wrinkles, pitting, or
honeycomb-reticulation (use magnification).
18. Longer perianth bristles usually half as long as the achene or shorter.
19. Culms and leaves usually < 1 mm wide; longer leaves equaling
the flowering culms in length; culms weakly ascending to reclining,
usually 50 cm or less tall; spikelets 2–3.2 mm long, with
scales usually slightly notched at apex and with minute awn
arising in notch (observe closely since sometimes folded and
not appearing notched) ___________________________________ R. debilis
19. Culms and leaves 1–4 mm wide; leaves not as long as the flowering
culms; culms stiffy erect, 40–130(–150) cm tall; spikelets
(3–)3.5–5 mm long, with scales usually not notched, tipped by
a minute awn ________________________________________ R. fascicularis
18. Longer perianth bristles as long as to longer than the achene.
20. Tubercle nearly as long as the achene or slightly longer, long
awl-shaped, 1.5–2 mm long _____________________________ R. gracilenta
20. Tubercle much shorter than achene, broadly deltoid, 0.4–0.7
(–0.9) mm long.
21. Culms and leaves usually 1 mm or less wide, filiform; achenes
0.9–1.2 mm long, 0.6–0.8 mm wide; tubercle margins setose
(= with minute bristles; use dissecting scope or strong
hand lens) __________________________________________ R. filifolia
21. Culms and leaves 1.5–4 mm wide, coarser than filiform;
achenes 1.3–1.9 mm long, 1–1.5 mm wide; tubercle margins
not setose ___________________________________ R. fascicularis