10. Kyllinga Rottb.
Plants annual or
perennial, sometimes with rhizomes. Aerial stems few to usually many per plant,
erect to spreading, solid, unbranched, triangular in cross-section and
sometimes ribbed when dried, glabrous. Leaves basal, 1–5 per aerial stem,
the lowermost 1–2 often reduced to bladeless sheaths, the sheath without
a ligule, often brown or reddish purple, the leaf blade spreading to ascending,
flat or somewhat folded lengthwise, the margins and midrib finely saw-toothed.
Inflorescences terminal, short, sessile, headlike spikes, these 1–3 per
stem, subtended by 2–4(–5), spreading to reflexed, leaflike bracts,
composed of numerous sessile spikelets. Spikelets flattened, 2-ranked, with 2
more or less opposite, larger scales and 1–2 highly reduced scales
(usually visible only with magnification) at the spikelet base, 1 of the larger
scales with a fertile floret, the other sometimes with a reduced, sometimes nonfunctional,
staminate floret, shed as an intact unit from the inflorescence axis at
fruiting. Perianth (bristles or scales) absent. Stamen 1–3. Styles not
expanded at the base, not persisting on the fruit as a tubercle . Stigmas 2.
Ovaries and fruits naked, without a perigynium (saclike covering). Fruits
1–2 mm long, ovate to oblong or elliptic in outline, biconvex, flattened,
the surface white or green, turning tan or light brown, minutely pebbled,
somewhat shiny. Forty to 45 species, North America to South America, Caribbean
Islands, Africa, Madagascar, Asia, south to Australia.
Kyllinga is the
most widely accepted segregate of Cyperus, although some botanists
continue to treat it as a subgenus of that genus. It differs from Cyperus
in a number of subtle characters, including the unique 4-scaled, 1-fruited
spikelets, which are dispersed as intact units.