67. Paspalum L. (bead grass)
Plants with C4 photosynthesis, annual or
perennial, sometimes with rhizomes or stolons, forming tufts, clumps, or mats.
Flowering stems erect to spreading, sometimes rooting at the lower nodes,
glabrous or hairy at the nodes. Leaf sheaths glabrous or hairy, the ligule a
membrane (a line or band of hairs elsewhere). Leaf blades usually flat, the
base rounded or abruptly narrowed, glabrous or hairy. Inflorescences panicles
with (1)2 to many spikelike branches, these alternate or rarely opposite or
whorled along the main axis, not rebranched. Spikelike branches appearing 1‑sided,
with many spikelets loosely to more commonly densely spaced nearly the entire
length, the axis flattened or slightly trigonous, with a spikelet at the tip or
extended past the uppermost spikelet into a short, pointed, sterile tip,
persistent (shed eventually after fruiting in P. repens). Spikelets
mostly in 2 or 4 rows (actually 2 rows of paired spikelets) on 1 side of the
axis, disarticulating below the glumes, not subtended by bristles or spines,
without a cuplike ring or knoblike disk at the base. Lower glume absent or less
commonly present, but very short. Upper glume about as long as the rest of the
spikelet, not inflated or saclike at the base, rounded or pointed at the tip,
awnless. Lowermost floret sterile, the palea absent or highly reduced, the
lemma about as long as the rest of the spikelet, rounded or pointed at the tip,
awnless. Fertile (perfect) floret with the lemma slightly shorter than that of
the sterile floret, rounded or bluntly pointed at the tip, awnless, nerveless
or obscurely nerved, glabrous, usually shiny, thickened and hard (usually
somewhat bonelike) at maturity, the margins also thick, wrapped around the
palea and fruit, including the tip (after flowering). Paleas glabrous, shiny or
dull, thickened and hard (usually somewhat bonelike) at maturity. Fruits mostly
broadly oblong‑elliptic in outline. About 250 species, nearly worldwide,
most diverse in the New World tropics.
Several species of Paspalum are commercially
important as forage crops in the tropics, especially P. dilatatum. Some
of the native Missouri species, including P. laeve and P. setaceum,
also are considered good forage grasses when present in sufficient density
(Crins, 1991).