JOHNSONGRASS, Sorghum holepense
(L.) Pers. 1, stout stem base, roots, and a young rhizome; 2,
panicle; 3, group of spikelets; 4, section of stem showing
base of leaf; 5, seed. Perennial, reproducing by large rhizomes
and seeds. Root system freely branching, fibrous. Rhizomes stout,
creeping, with purple spots, usually with scales at the nodes. Stems
erect, stout, from 1-1/2 to 6 feet (0.45 to 1.8 m) or more tall. Leaves
alternate, simple, smooth, 6 to 20 inches (15 to 50 cm) long, about 1/2
to 1-1/2 inches (1.3 to 3.8 cm) wide. Panicles large, purplish,
hairy. Seed nearly 1/8 inch (3 mm) long, oval, reddish-brown, marked
with fine lines on surface, bearing a conspicuous awn easily broken off.
Found especially on rich soil. Troublesome in corn and soybeans
on overflow bottoms. Difficult to control or eradicate. Listed as noxious
weed in states where found.