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

508 CYPERACEAE
1. Pistil (and later achene) enclosed in a pouch or sac (= perigynium) from which the style is exserted
during flowering; flowers imperfect __________________________________________________ Carex
1. Pistil (and later achene) not enclosed in a perigynium (but subtended by a flat or concave scale);
flowers perfect (imperfect in Scleria).
2. Scales of spikelets (= scale-like bracts also referred to as floral scales or simply scales) 2-ranked
(= in two distinct rows), the spikelets ± flattened or square in cross section.
3. Culms without any leaf blades or leafy bracts (leaves reduced to basal sheaths); spikelets
with 2–4(–9) scales; inflorescences without any branching whatsoever, of a solitary terminal
spikelet; achenes with a tubercle (= cap-like persistent style base differing in appearance
from achene) (in East TX only 1 species of Eleocharis (E. baldwinii) has the scales of
spikelets 2-ranked) ___________________________________________________ Eleocharis baldwinii
3. Culms (= stems) with leaf blades or leafy bracts at least below the inflorescence; spikelets
with 1-many scales; inflorescences often conspicuously branched, of few–many spikelets;
achenes without a tubercle; including species extremely abundant in East TX.
4. Inflorescences widely spaced in the axils of leaves/bracts with well-developed sheaths;
perianth bristles present, 6–9 per flower ________________________________________ Dulichium
4. Inflorescence branches apically clustered and subtended by sheathless bracts; perianth
bristles absent.
5. Plants small (culms 40(–55) cm or less tall); inflorescence a single unlobed or 3-lobed
(but unbranched) terminal structure; spikelets with only 2 well-developed scales (also
with 2 minute, brownish, basal scales) and only 1 bisexual fertile flower; each spikelet
with only 1 achene; achenes lenticular (= lens-shaped); styles 2-branched _____________ Kyllinga
5. Plants variable in size, but often much larger than 40 cm tall; inflorescence often obviously
branched; spikelets usually with 4–many scales and 3–many bisexual flowers;
each spikelet with > 1 achene; achenes usually trigonous (= 3-sided) OR in a few
species lenticular; styles usually 3-branched OR in a few species 2-branched ___________ Cyperus
2. Scales of spikelets spirally arranged, not 2-ranked, the spikelets round OR scales only 2 per spikelet.
6. Scales of spikelets white; spikelets in a terminal, leafy-bracted head-like cluster, the bracts
with white bases; style branches 2 ____________________________________________ Rhynchospora
6. Scales of spikelets variously colored (may rarely be partly white); inflorescences various,
but not with white-based bracts; style branches 2 or 3.
7. Inflorescences with a single spikelet, this terminal, the inflorescences thus without any
branching whatsoever; culms without leaf blades or leafy bracts; achenes with a tubercle
(= cap-like persistent style base at apex of achenes, differing in appearance from
actual achene) ____________________________________________________________ Eleocharis
7. Inflorescences with 1–many spikelets, these terminal or lateral, the inflorescences thus
unbranched OR often conspicuously branched; culms with leaf blades (at least basal
ones) or leafy bracts; achenes with or without a tubercle.
8. Achenes with whitish or light grayish, bony or crustaceous, outer layer (pericarp),
usually sitting on a distinct hardened ring-like or disk-like pad (= hypogynium);
flowers unisexual ____________________________________________________________ Scleria
8. Achenes with neither whitish, light grayish, bony, nor crustaceous outer layer, nor
sitting on a distinct, hardened, ring-like or disk-like pad; flowers bisexual.
9. Achenes with a prominent tubercle; spikelets usually 1–few-flowered, the uppermost
1–2 florets usually without pistil; lower (1–)2–3 scales of spikelets usually
sterile ____________________________________________________________ Rhynchospora
9. Achenes without tubercle (except in Bulbostylis, which has thread-like leaves); spikelets
1–many-flowered, all florets with pistil; only lowest scale of spikelet usually
sterile (except in Cladium which usually has more than 1 sterile lower scale).
10. Scales of spikelets with prominent bristle-tip longer than width of scale base;
perianth of 3 stalked-bladed perianth scales, these sometimes alternating with
3 bristles ____________________________________________________________ Fuirena