Flora of North America species comparison

annual, 20-500 cm tall, aerenchymatous, sometimes floating.

50-150 cm, spongy, developing adventitious roots at the nodes, branched;

branches erect, leafy.

aerenchymatous;

auricles present or absent;

ligules membranous or scarious, sometimes absent;

pseudopetioles sometimes present;

blades with parallel veins, cross venation not evident;

abaxial blade epidermes with microhairs and transversely dumbbell-shaped silica bodies;

first seedling leaf without a blade.

cauline, glabrous, veins tessellate;

sheaths open, inflated, serving as floats;

ligules absent or hyaline;

pseudopetioles present;

blades elliptic, ovate, ovate-lanceolate, or oblong.

usually panicles, sometimes racemes or spikes;

disarticulation below the spikelets, not occurring in cultivated taxa.

terminal panicles, aerial, lowermost branches whorled;

disarticulation beneath the spikelet calluses.

laterally compressed or terete, with 1 bisexual or unisexual floret, sometimes with 2 sterile florets below the sexual floret, these no more than 1/2 (9/10) the length of the fertile floret;

unisexual spikelets in the same or different panicles;

rachillas not prolonged.

bisexual, laterally compressed, with 1 floret.

absent or highly reduced, forming an annular ring or lobes at the pedicel apices;

sterile florets 1/8 – 1/2 (9/10) as long as the spikelets;

fertile lemmas 3-14-veined, membranous or coriaceous, apices entire, unawned or with a terminal awn;

paleas similar to the lemmas, 3-10-veined, 1-keeled;

lodicules 2;

anthers usually 6(1-16);

styles 2, bases fused or free, stigmas linear, plumose.

absent or an annular rim;

calluses (1)2-10 mm, stipelike, glabrous, junction with the pedicels marked by a tan constriction;

lemmas 5-veined, margins clasping the paleas, apices acuminate, awned, awns terminal, antrorsely scabridulous;

paleas similar to the lemmas, 3-veined, 1-keeled, acute-acuminate, unawned;

lodicules 2, glabrous;

anthers 6;

styles 2, bases not fused, stigmas laterally exserted, plumose.

terete, fusiform;

embryos small;

hila linear, almost as long as the embryo, x = 12.

usually caryopses, sometimes achenes, ovoid, oblong, or cylindrical;

embryos of the F+FP or F+PP type, small or elongate, with or without a scutellar tail;

hila usually linear, x = 12, 15, 17.