Aquatic perennials; culms prostrate, decumbent and
rooting at the lower nodes, then ascendent, succulent; internodes
spongy, hollow, greenish to pale, glabrous; nodes
compressed, dark; sheaths open, striate, longer or shorter
than the internodes, with aerenchyma, pale, glabrous;
ligules membranous-ciliate; collar brown; blades oblonglanceolate
to linear-lanceolate. Inflorescence an open panicle,
with first and second order branches diverging from the
main axis, lower branches pseudoverticillate to opposite,
the upper ones alternate; main axis triquetrous, wavy, pulvini
glabrous; spikelets solitary or paired on third order
branches; pedicels scabrous, triquetrous. Spikelets lanceolate,
green to pale brown, dorsiventrally compressed,
dissarticulating below the lower glume, glabrous, upper
glume and lower lemma subequal, membranous, longer
than the upper anthecium, acuminate; lower glume reduced,
hyaline; lower palea reduced or absent, lower flower absent;
upper anthecium smooth and shining, indurate, acuminate,
with sparse macrohairs toward the apex or glabrous; palea
2-nerved, lanceolate; lodicules 2, conduplicate. Caryopsis
plano-convex; hilum linear, nearly 1/2 or as long as the
caryopsis, embryo less than half the length of the caryopsis.
Distribución:
Género con dos especies, una americana, ampliamente distribuida desde Mesoamérica hasta la Argentina y la restante creciendo en África.
