Scientific NameSorghum halepense
Synonyms (former Scientific Names):
Johnsongrass is a course, generally clumping grass, and one of the most troublesome perennial grasses in the U.S. Growth is surged by thick aggressive rhizomes and flowering last from June to July.
The plant can grow 6 to 7 ft height. It has a fringed membranous ligule (2.0-5.5mm long). Leaf blades are 20 to 60 cm long and 10-30 mm wide at maturity and have a thick white midvein. The leaf blade and sheath are hairless beside a few sparse hairs near the collar.
Johnsongrass can spread through seed or rhizomes.
Flower Seed Head
The seedhead flowers May through October. The seedhead is an open panicle (12-50 cm long) with numerous branches and has an overall pyramid outline. The seedhead starts out green but by maturity it turns dark reddish or purple brown.
The seed is produced on the shorter floret which is 4-5.5 mm long. The seed itself is oval shaped, long dark reddish brown(3-5mm long).
Johnsongrass prefers rich soils and doesn't tolerate close mowing. It grows in cultivated, reduced-tillage, and perennial cops.
Leaf Hair on Upper Surface
rolled in bud
Mature Leaf Width
more than 15 mm
more than 3 mm