brown, green, purple, yellow
April - November
0.5 - 2.0
Leaves flat with white midrib, ligule thin, papery, spikelets in paris at the nodes, half on stalks, all are hairy.
Seeds are difficult to germinate when fresh and benefit from three to five months of dry storage in which time they after-ripen (Harrington 1916, 1917). Best germination is obtained at alternating temperatures of 77-104 F (25-40 C). Johnsongrass can also be propagated vegetatively by rhizome cuttings, each with at least one eye, planted 1/2" deep (McWhorter 1961). Anderson et al. (1960) found the rhizomes to remain viable, even after drying. Commercial seed has a purity of 98%, a germination rate of 85%, and 118,000-121,000 seeds/lb. The recommended planting rate is 10-25 lbs/acre (USDA 1948).
Produces palatable forage.
Naturalized and invasive throughout the Gulf Coast where it is often used as a forage grass. It is reported to decline under moderate, continuous grazing. When grazed under stress conditions, or after a hard frost, it can cause prussic acid poisoning in animals. It is sometimes infected with ergot (Claviceps purpurea), a parasitic fungus that appears as a purplish black, banana-shaped sclerotia which replaces some of the seed in the floret. It is most common in rye, wildrye, and Dallas grass but is found in many other grasses and Rhyncospora sp. It occurs throughout the world but is not usually common enough to cause trouble. The poisonous compound is "ergotoxine," which is poisonous to cattle, sheep, horses and man. It has a cumulative effect if eaten over time. Two types of poisoning may occur, gangrenous and nervous, both the result of damage to the circulatory system. Acute poisoning may produce paralysis of the limbs and tongue, stomach upset and abortion. Chronic poisoning can result in gangrene of the limbs. Delirium, spasms, and paralysis may occur before death. Mowing to cut off seed heads of infected plants has been helpful in preventing poisoning of livestock. Sorghum halepense is apparently native to the Mediterranean region but is not widespread throughout the world.
Open ground, fields, waste places.