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

CYPERUS/CYPERACEAE
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21. Leaf blades often wider, 1–4 mm wide; achenes � ellipsoid,
0.8–1.2 mm wide; anthers 0.3–0.7 mm long; scales of
spikelets off-white to light reddish brown ______________ C. lupulinus
17. Scales of spikelets with 1 nerve, usually 1–2 mm long, 2-keeled in basal
1/3–2/3 (use magnification; the two keels are close together, with a groove
between them; this character is best seen when the scale is viewed from
its back (= abaxial side)); achenes 0.7–1.5 mm long.
22. Leaf blades, leaf sheaths, and bracts conspicuously nodulose (= with
knot-like septa visible under a hand lens) owing to numerous cross
veins between the main veins (especially visible on lower surface);
culms sharply 3-angled, scabrous on angles only.
23. Scales of spikelets oblanceolate, usually 1.7–2.5 mm long; inflorescences
with 5–12 rays (= main branches); achenes 1.2–1.5 mm
long; spikelets (1.7–)2.2–3.2 mm wide ___________________________ C. virens
23. Scales of spikelets ovate, 1.4–1.6 mm long; achenes 1–1.2 mm long;
inflorescences with 3–5 rays; larger spikelets 1.5–2.2 mm wide
___________________________________________________ C. drummondii
22. Leaf blades, leaf sheaths, and bracts not nodulose; culms 3-angled to
nearly rounded, usually smooth (except retrorsely scabrous in C.
surinamensis).
24. Culms rough to the touch, sparsely to densely covered with microscopic
retrorse (= down-pointing) teeth; achenes 0.7–0.9 mm
long _______________________________________________ C. surinamensis
24. Culms smooth to the touch, rarely with a few horizontal knobs;
achenes 0.8–1.5 mm long.
25. Inflorescence bracts 3–4, the longest erect or nearly so, appearing
as a continuation of the culm; scales of spikelets reddish
laterally ____________________________________________ C. reflexus
25. Inflorescence bracts 4–8(–10), all horizontal to ascending, but
none appearing as a continuation of the culm; scales of spikelets
pale to greenish or yellowish brown or light brown laterally.
26. Spikelets (5–)7–10(–rarely longer) mm long; anthers 0.8–
1.2 mm long; achenes broadly ellipsoid ________________ C. ochraceus
26. Spikelets 4–6.5 mm long; anthers 0.6–0.7 mm long;
achenes narrowly ellipsoid to ellipsoid ______________ C. entrerianus
7. Spikelets in spikes (sometimes head-like), spread out along a distinct axis, not arising at the
same point (the axis, however, is sometimes quite short and concealed by crowded spikelets;
it is sometimes necessary to spread and/or remove the spikelets and look carefully at their
attachment points).
27. Spikelet axis (= rachilla) separating at maturity at the base of each spikelet scale, the mature
spikelet disarticulating into segments consisting of a scale, internode, and achene
clasped by rachilla wings (in immature spikelets, the only obvious sign of this is that the
spikelet axis (= rachilla including its wings) becomes thickened, spongy or corky, and
light-colored (subgenus Diclidium) _____________________________________________ C. odoratus
27. Spikelet axis remaining intact or apparently so, the florets either falling separately from
the persistent axis OR the entire axis falling as a unit (OR unclear in immature C. odoratus).
28. Spikelets of a spike � perpendicular to the spike axis to markedly reflexed, enough of
them reflexed to give the general appearance of the spikelets drooping around the
spike axis.
29. Spikes oblong, not wider toward apex, ca. 1/2 as wide as long; culms smooth;
leaves and bracts smooth except for marginal prickles ______________ C. hystricinus (in part)