Plants perennial; rhizomatous. Culms 50-200 cm tall, 0.4-2 cm thick;
nodes appressed pubescent; internodes glabrous. Ligules 2-6
mm, membranous, conspicuously ciliate; blades 10-90 cm long, 8-40 mm wide.
Panicles 10-50 cm long, 5-25 cm wide, primary branches compound, terminating
in rames of 1-5 spikelet pairs; disarticulation usually beneath the sessile
spikelets, sometimes also beneath the pedicellate spikelets. Sessile spikelets
bisexual, 3.8-6.5 mm long, 1.5-2.3 mm wide; calluses blunt; glumes
indurate, shiny, appressed pubescent; upper lemmas unawned, or with a geniculate,
twisted awn to 13 mm; anthers 1.9-2.7 mm. Pedicels 1.8-3.3 mm. Pedicellate
spikelets staminate, 3.6-5.6 mm; glumes membranous to coriaceous, unawned.
Caryopses not exposed at maturity. 2n = 20, 40; several dysploid
counts also reported.
Sorghum halepense is native to the Mediterranean region. It is sometimes
grown for forage in North America, but it is considered a serious weed in warmer
parts of the United States. It hybridizes readily with S.
bicolor, and derivatives of such hybrids are widespread. The annual Sorghum
almum Parodi, which has wider (2-2.8
mm) sessile spikelets with more veins in the lower glumes (13-15 versus 10-13)
than S. halepense, is one such derivative.
Robust perennial to 1.5 m, colonial by long rhizomes; lvs elongate, 1-2 cm wide; panicle 1.5-4 dm, open, its main axis glabrous or scabrous; sessile spikelet silky, 4-6 mm, the pediceled one staminate (or neuter), glabrous, slightly longer; awn 1-1.5 cm; 2n=40. Native to the Mediterranean region, cult. for forage, escaped and well established as a weed especially in the s. part of our range, but also n. to Mass. and Mich. (Holcus h.; S. miliaceum) Under some conditions the plant becomes poisonous through the production of prussic acid. Johnson-grass is the result of hybridization with cult. sorghum.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.