Panicum amarum
Panicum hemitomon
bitter beachgrass, bitter panicgrass, bitter panicum
maidencane, mountain panic
20-250 cm tall, 3-10 mm thick, erect or decumbent, simple or branched from the lower nodes;
nodes glabrous;
internodes glabrous, glaucous.
50-200 cm, mostly erect and sterile, glabrous, often rooting from the lower nodes if submerged.
shorter or longer than the internodes, not keeled, glabrous;
collars often glaucous and purplish;
ligules 1-5 mm;
blades 7-50 cm long, 2-13 mm wide, erect or ascending, firm, thick, flat basally, more or less involute towards the apices.
usually glabrous, or pilose or hirsute at the lowermost sheath, especially distally;
ligules shorter than 1 mm;
blades 8-35 cm long, 5-15 mm wide, ascending or spreading, abaxial surfaces glabrous, adaxial surfaces usually scabridulous or pubescent, bases slightly narrowed, margins scabrous, apices long-tapering.
10-80 cm long, 2-17 cm wide, contracted, slightly nodding;
primary branches whorled or opposite, strongly ascending to appressed;
pedicels 0.5-15 mm, appressed to slightly divergent.
10-30 cm long, less than 1 cm wide;
branches mostly short, appressed-ascending, with fascicles of congested spikelets; ultimate branchlets 1-sided;
pedicels 0.2-1.8 mm.
4-7.7 mm long, 1.5-2 mm wide, narrowly ovoid, glabrous, acuminate;
lower florets staminate.
2-2.8 mm, subsessile, lanceoloid, slightly laterally compressed, glabrous, acute.
and lower lemmas relatively thick;
lower glumes 2.8-4 mm, 1/2 - 4/5 as long as the spikelets, 3-9-veined, apices of the midveins sometimes scabridulous;
upper glumes and lower lemmas extending 1.5-3 mm beyond the upper florets, apices stiffly gaping;
upper glumes 3.9-7.6 mm, 5-9-veined;
lower lemmas slightly shorter than the upper glumes, 7-9-veined, lower paleas 3-7 mm, oblong-hastate, folded over the anthers;
lower florets staminate;
upper florets 2.4-3.9 mm long, 1-1.8 mm wide, narrowly ovoid to oblong, glabrous, smooth, shiny, lemma margins clasping the paleas only at the base.
glumes about 1/2 as long as the spikelets, slightly keeled along the midveins, 3-veined, acute;
upper glumes and lower lemmas similar, glumes slightly shorter than the lemmas, faintly keeled on the back, acute;
lower florets staminate;
lower paleas subequal to the lower lemmas;
upper florets 2-2.5 mm, 2/5 to almost as long as the spikelets, narrowly ellipsoid;
upper lemmas relatively thin, flexible, pale, acuminate, clasping the paleas only at the base.
= 36, 54.
= 36, 40.
Panicum amarum
Panicum hemitomon
Panicum amarum grows in the coastal dunes, wet sandy soils, and the margins of swamps, along the Atlantic Ocean and the Gulf of Mexico from Connecticut to northeastern Mexico. It is also known, as an introduction, from a few inland locations in New Mexico, North Carolina, and West Virginia, as well as in the Bahamas and Cuba.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Panicum hemitomon forms extensive, nearly pure stands in water or wet soils such as marshes, swamps, and along the shores of streams, canals, ditches, lakes, and ponds. It is restricted to the United States.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Rhizomes short or ascending; culms often bunched and decumbent, usually more than 120 cm tall; lower glumes with 3-5 less evident veins, the midvein smooth distally; spikelet density high; panicles with 2 or more main branches per node; spikelets 4-5.9 mm long | subsp. amarulum |
1. Rhizomes horizontally elongate; culms mostly solitary, less than 150 cm tall; lower glumes with 7-9 prominent veins, the midvein scabridulous distally; spikelet density moderate; panicles with 1 or 2 main branches per node; spikelets 4.7-7.7 mm long | subsp. amarum |
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