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.

30-150 cm tall, 3-7 mm thick, compressed, spongy, glabrous, decumbent and rooting at the lower nodes in shallow water;

nodes glabrous;

internodes glabrous, smooth.

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.

usually shorter than the internodes, not keeled, glabrous or sparsely hispid distally;

ligules 1-4 mm;

blades 10-40 cm long, 5-15 mm wide, flat, glabrous, contracted basally, attenuate distally, apices acute.

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.

10-25 cm long, 5-17 cm wide, shortly exserted or included basally;

primary branches 4-12 cm, ascending to spreading, secondary and higher order branches confined to the distal 2/3, pedicels 1-4 mm, sharply 3-angled, ascending to appressed.

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.

3-4 mm long, 0.8-2 mm wide, lanceolate.

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.

0.5-0.9 mm, 1/5 – 1/3 as long as the spikelets, rounded, glabrous, truncate, weakly 1-3-veined;

upper glumes and lemmas subequal, glabrous, 9-11-veined, veins prominent, apices acute to accuminate;

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

lower florets sterile;

upper florets 2-2.7 mm, narrowly ellipsoid, smooth, shiny, yellowish.

= 36, 54.

= 54.