Panicum virgatum
Panicum coloratum
panic raide, switch grass, switch panicgrass
kleingrass
40-300 cm tall, 3-5 mm thick, solitary or forming dense clumps, erect or decumbent, usually simple;
nodes glabrous;
internodes hard, glabrous or glaucous, green or purplish.
50-140 cm tall, 1.5-2.5 mm thick, usually erect, rarely decumbent, firm;
nodes glabrous or puberulent;
internodes glabrous.
longer than the lower internodes, shorter than those above, glabrous or pilose, especially on the throat, margins usually ciliate;
ligules 2-6 mm;
blades 10-60 cm long, 2-15 mm wide, flat, erect, ascending or spreading, glabrous or pubescent, adaxial surfaces sometimes densely pubescent, particularly basally, bases rounded to slightly narrowed, margins scabrous.
shorter than the internodes, glabrous or hispid, hairs papillose-based, rounded basally;
ligules 0.5-2 mm;
blades 10-30 cm long, 2-8 mm wide, flat, glabrous or sparsely hirsute on 1 or both surfaces.
10-55 cm long, 4-20 cm wide, exserted, open;
primary branches thin, straight, solitary to whorled or fascicled, ascending to spreading, scabrous, usually rebranching once;
pedicels 0.5-20 mm, appressed to spreading.
4-25(40) cm long, 3-14 cm wide, exerted, lax;
primary branches 3-14 cm, opposite and alternate, ascending, glabrous, branching in the distal M;
pedicels 1-4 mm, appressed or spreading.
2.5-8 mm long, 1.2-2.5 mm wide, narrowly lanceoloid, turgid to slightly laterally compressed, glabrous, acuminate.
2.5-3.5 mm long, 1-1.2 mm wide, narrowly ovoid to ellipsoid, glabrous, acute.
glumes 1.8-3.2 mm, 1/2 - 4/5 as long as the spikelets, glabrous, 5-9-veined, acuminate;
upper glumes and lower lemmas extending 0.4-3 mm beyond the upper florets, 7-11-veined, strongly gaping at the apices;
lower florets staminate;
lower paleas 3-3.5 mm, ovate-hastate, lateral lobes folded over the anthers before anthesis;
upper florets 2.3-3 mm long, 0.8-1.1 mm wide, narrowly ovoid, smooth, glabrous, shiny;
upper lemmas clasping the paleas only at the base.
glumes 1-1.5 mm, about 1/3 as long as the spikelets, glabrous, 1-3-veined, acute;
upper glumes slightly exceeding the lower lemmas, glabrous, acute, scarcely separated from the lower lemmas;
lower florets staminate;
lower lemmas similar to the upper glumes;
lower paleas 2-3 mm, oblong;
upper florets 2-2.5 mm long, 0.8-1 mm wide, ellipsoid, widest below the middle, glabrous, smooth, shiny, apices lightly beaked.
= 18, 21, 25, 30, 32, 35, 36, 54-60, 67-72, 74, 77, 90, 108.
= 18, 36, 41, 42, 43, 45, 54, 63 (United States material apparently usually tetraploid, with 2n = 36).
Panicum virgatum
Panicum coloratum
Panicum virgatum grows in tallgrass prairies, especially mesic to wet types where it is a major component of the vegetation, and on dry slopes, sand, open oak or pine woodlands, shores, river banks, and brackish marshes. Its range extends, primarily on the eastern side of the Rocky Mountains, from southern Canada through the United States to Mexico, Cuba, Bermuda, and Costa Rica, and, possibly as an introduction, in Argentina. It has also been introduced as a forage grass to other parts of the world.
Panicum virgatum is an important and palatable forage grass, but its abundance in native grasslands decreases with grazing. Several types are planted for range and wildlife habitat improvement. Plants from eastern New Mexico, western Texas, and northern Mexico tend to have larger spikelets (6-8 mm versus 2.5-5.5 mm) and are sometimes called P. havardii Vasey Tetraploids appear to be the most common ploidy level, especially in the upper midwest and northern plains, with higher ploidy levels being more common southwards, but plants in a small area can range from diploid through duodecaploid, with dysploid derivatives. If morphological markers matched chromosome numbers and ecotypic characters, the species could be considered an aggregate of numerous microspecies. In the absence of such correlations, it must be regarded as simply a wide-ranging, highly variable taxon. Plants identified as Panicum virgatum var. cubense Griseb. and P. virgatum var. spissum Linder represent end points of geographic clines.
Panicum virgatum is not always readily separable from P. amarum, particularly P. amarum subsp. amarulum; future work may support their treatment as conspecific taxa.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Panicum coloratum is an African species that has been widely introduced into tropical and subtropical regions around the world. It is now established in the Flora region, growing in open, usually wet ground; it is also occasionally cultivated as a forage grass.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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