Panicum amarum
Panicum obtusum
bitter beachgrass, bitter panicgrass, bitter panicum
vine mesquite
20-250 cm tall, 3-10 mm thick, erect or decumbent, simple or branched from the lower nodes;
nodes glabrous;
internodes glabrous, glaucous.
20-80 cm, often in small clumps, compressed, erect or decumbent, glaucous;
lower nodes pubescent;
upper nodes glabrous.
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.
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.
5-15 cm long, 0.8-1.5 cm wide;
branches 2-6, spikelike, erect, puberulent, 3-angled; ultimate branchlets 1-sided;
pedicels paired, congested, shorter pedicels 0.1-1 mm, longer pedicels 1.5-2.5 mm.
4-7.7 mm long, 1.5-2 mm wide, narrowly ovoid, glabrous, acuminate;
lower florets staminate.
2.8-4.4 mm, ellipsoid, terete to slightly laterally compressed, glabrous, obtuse.
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.
sheaths ascending, pubescent to pilose;
upper sheaths glabrous;
ligules 0.2-2 mm, membranous, truncate, irregularly denticulate;
blades 3-26 cm long, 2-7 mm wide, ascending, firm, glaucous, sparsely pilose near the base, often scabrous on the margins, involute towards the apices.;
lower glumes about 3/4 as long as the spikelets, 5- or 7-veined;
upper glumes and lower lemmas equaling the spikelets, 5-9-veined;
lower florets staminate;
lower paleas 2.5-3.5 mm;
upper florets puberulent at the bases and apices.
= 36, 54.
= 20, 36, 40.
Panicum amarum
Panicum obtusum
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 obtusum grows in seasonally wet sand or gravel, especially on stream banks, ditches, roadsides, wet pastures, and rangeland. Its range extends from the southwestern United States to central Mexico. Flowering is from May through October.
(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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