Panicum amarum
Panicum amarum subsp. amarulum
bitter beachgrass, bitter panicgrass, bitter panicum
coastal panicgrass
20-250 cm tall, 3-10 mm thick, erect or decumbent, simple or branched from the lower nodes;
nodes glabrous;
internodes glabrous, glaucous.
usually 100-250 cm, robust, decumbent, densely bunched (occasionally with more elongated rhizomes and less bunching in the southern part of its range).
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.
usually more than 5 cm wide, spikelet density high;
primary branches usually 2 or more per node, smooth to moderately scabrous, usually with quaternary branching.
4-7.7 mm long, 1.5-2 mm wide, narrowly ovoid, glabrous, acuminate;
lower florets staminate.
4-5.9 mm;
lower glumes 3-5-veined, veins less evident than in subsp. amarum, midvein smooth distally.
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.
= 36, 54.
Panicum amarum
Panicum amarum subsp. amarulum
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 amarum subsp. amarulum grows in swales behind the first dune and on sandy borders of wet areas. It extends as far north as northern New Jersey and extends southward into Mexico. It has been introduced to Massachusetts, West Virginia, Cuba, and the Bahamas.
Panicum amarum subsp. amarulum is a fertile tetraploid, and possibly a progenitor of subsp. amarum, with which it intergrades in the Gulf region. Plants that intergrade with P. virgatum are evident in some coastal areas; they may represent hybrids.
(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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