Eastern Forest Threat Center - Johnsongrass

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Johnsongrass in June

Johnsongrass in June

Ted Bodner, Southern Weed Science Society, Bugwood.org

Sorghum halepense

Johnsongrass, native to the Mediterranean region, was introduced into the U.S in the early 1800s for use as a forage crop.

Keywords: Poaceae, perennial, grass, dense clumps, solid stands, lanceolate leaves, hairy panicles, spikelets, conspicuous awn, rhizomes

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Threat Description

Johnsongrass is a tall rhizomatous perennial grass that grows in dense clumps or nearly solid stands reaching up to 8 ft. in height. Its leaves are smooth, lanceolate with a white mid vein, alternately arranged, and 2 ft. long. Stems are pink to rusty red near the base. Flowers are large, loosely branched, purplish, hairy panicles. Spikelets occur in pairs or threes, and each has a conspicuous awn. Johnsongrass reproduces vegetatively and by prolific reddish-brown seeds. This species occurs in crop fields, pastures, abandoned fields, rights-of-way, forest edges, ditches, and wetlands. It thrives in open, disturbed, rich, bottom ground, particularly in cultivated fields. It spreads aggressively and can form dense colonies, displacing native vegetation and restricting tree seedling establishment.