Flora of North America species comparison

5-200 cm tall, 0.4-3 mm thick, decumbent to erect, commonly geniculate to ascending, rooting at the lower nodes when in water, simple to divergently branched from the lower and middle nodes, usually succulent, slightly compressed, glabrous;

nodes usually swollen, sometimes constricted on robust plants, glabrous;

internodes glabrous, shiny, pale green to purplish.

40-100 cm, erect, simple or branching from the lower nodes;

nodes glabrous;

internodes glabrous.

compressed, inflated, sparsely pubescent near the base, elsewhere mostly glabrous, sparsely pilose, or hispid, hairs sometimes papillose-based, margins or throat ciliate, with papillose-based hairs;

ligules 0.5-2 mm;

blades 10-65 cm long, 3-25 mm wide, glabrous or sparsely pilose, often scabrous near the margins, midribs stout, whitish.

shorter than the internodes, usually glabrous, lower sheaths sometimes pilose at the summit, hairs papillose-based;

ligules 0.1-0.4 mm;

blades 4-19 cm long, 1.5-4 mm wide, mostly involute at maturity, erect, firm, abaxial surfaces usually glabrous, adaxial surfaces often sparsely pilose, particularly basally.

4-40 cm, diffuse, lax, with a few spikelets;

branches to 15 cm, alternate or opposite, occasionally verticillate, ascending to spreading, stiff, scabrous;

pedicels 1-6 mm, sharply 3-angled, scabrous, expanded to cuplike apices, appressed mostly to the abaxial side of the branches.

3-12 cm long, less than 1 cm wide, contracted, with few spikelets;

branches 1-4 cm, few, ascending-appressed; ultimate branchlets 1-sided;

pedicels 0.5-3 mm, scabridulous, appressed, usually with a few slender hairs at the apices.

1.8-3.8 mm long, 0.7-1.2 mm wide, ellipsoid to narrowly ovoid, light green to red-purple, glabrous, acute to acuminate.

1.8-2.8 mm long, 0.8-1 mm wide, usually subsessile, lanceoloid to narrowly ovoid, green, often purplish-stained, glabrous, acute.

0.6-1.2 mm, 1/4 - 1/3 as long as the spikelets, 0-3-veined, obtuse to acute;

upper glumes and lower lemmas similar, exceeding the upper florets by 0.3-0.6 mm, 7-9-veined;

lower paleas vestigial to almost as long as the lower lemmas;

lower florets sterile;

upper florets 1.4-2.5 mm long, 0.7-1.1 mm wide, narrowly ellipsoid, smooth, shiny, stramineous to nigrescent, with pale veins.

0.9-3 mm, 1/2 - 2/3 as long as the spikelets, 1-3-veined, not keeled over the midveins, acute or obtuse;

upper glumes and lower lemmas subequal, 5-7-veined, midveins not keeled, acute to short-acuminate, occasionally gaping at the apices;

lower florets sterile;

lower paleas about 1/2 - 2/3 as long as the lower lemmas;

upper florets 1.1-1.8 mm long, 0.6-0.8 mm wide, 2/5 – 3/4 as long as the spikelets, lustrous, usually brownish, apices glabrous;

upper lemmas thick, stiff, clasping the upper paleas throughout their length.

= 36, 54.

= 20.