Scientific Name
Sorghum halepense (L.) Pers.
Common Name(s)
Johnsongrass
Tribe / Family Name
Andropogoneae
Flowering Period
July to September
Symbol
SOHA
Description
Johnsongrass is an introduced, warm-season, perennial rhizomatous grass. Culms range from 100-150 cm in height. Its inflorescences are panicles 10-50 cm long and up to 25 cm wide. Spikelets are borne in twos (rarely in threes) and consist of a sessile spikelet and a stalked spikelet (rarely with two stalked spikelets): the sessile spikelets are 4-6.5 mm long, bisexual, and unawned or awned (awns are up to 13 mm long, twisted, and geniculate); the upper stalked spikelets are 3-6 mm long, staminate, and unawned. Ligules are up to 6 mm long, membranous, and conspicuously ciliate. Blades are 10-90 cm long and up to 40 mm wide; larger leaf blades have prominent pale-colored central veins.
General Info
Johnsongrass can be found along roadsides, ditchbanks, and trails, in gardens and cropfields, and plains.
Similar Species
Johnsongrass is a distinctive grass and not usually confused with other grasses. If your grass doesn't have spikelets in pairs or trios, it's likely not Johnsongrass.
Picture of growth habit. The poser on the right is 6'4" and full of muscle. Thank you, Ryan, for being such a standup guy. Photo by Justin J. Trujillo.
Picture of growth habit. Photo by Justin J. Trujillo.
Close-up image of open panicle inflorescence. Photo by Justin J. Trujillo.
Close-up image of open panicle inflorescence. Photo by Justin J. Trujillo.
Close-up image of spikelet. Note the bottom middle sessile spikelet is bisexual and awned; the upper spikelet (in this case, the photo shows two spikelets, which is a rare occurrence) is stalked and staminate. Photo by Justin J. Trujillo.
Close-up picture of ligule. Note the ligule is a densely ciliate membrane. Photo by Justin J. Trujillo.
USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. <i>An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols.</i> Charles Scribner's Sons, New York. Vol. 1: 121.