Panicum amarum
Panicum gymnocarpon
bitter beachgrass, bitter panicgrass, bitter panicum
20-250 cm tall, 3-10 mm thick, erect or decumbent, simple or branched from the lower nodes;
nodes glabrous;
internodes glabrous, glaucous.
60-130 cm, thick, glabrous, rooting profusely at the lower nodes;
nodes glabrous, often with a dark green band.
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 shorter than the internodes, glabrous, prominently veined;
ligules 0.5-1.5 mm;
blades 15-40 cm long, 7-25 mm wide, tapering from midlength, flat, both surfaces glabrous, bases subcordate, margins scabrous to smooth, widest at the base, apices acute.
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.
10-40 cm long, 7-20 cm wide, open, with straight, rigid rachises;
branches whorled, stiffly ascending, with short, appressed, higher order branches; ultimate branchlets 1-sided, with solitary spikelets or small clusters of spikelets;
pedicels 0.1-1.5 mm.
4-7.7 mm long, 1.5-2 mm wide, narrowly ovoid, glabrous, acuminate;
lower florets staminate.
5.5-7 mm long, about 1 mm wide, narrowly lanceoloid, glabrous.
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.
spreading apart at maturity, keeled, prominently veined, scabrous along the midveins;
lower glumes nearly as long as the lower lemmas;
upper glumes and lower lemmas 3-veined, spreading, greatly exceeding the upper florets, lower lemmas longer than the upper glumes, arcuate;
lower florets sterile;
lower paleas thin;
upper florets 1.9-2.2 mm, less than 1/3 as long as the spikelets, obovoid, lustrous, pale to brownish, acute, often short-stipitate.
= 36, 54.
= 40.
Panicum amarum
Panicum gymnocarpon
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 gymnocarpon grows in swamps, wet woodlands, and the marshy shores of lakes and streams. It is also found occasionally in shallow water, often in the shade. 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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