Johnson grass (Sorghum halepense
) is a coarse, extremely competitive, perennial, rhizomatous grass that grows in clumps or nearly solid stands. It is thought to be native to the Mediterranean region but has been introduced to temperate regions worldwide.
- Roots: Fibrous with thick rhizomes.
- Stem:Green to maroon-colored sheath, especially near the base of the plant; Round to somewhat flattened.
- Leaves: Rolled in the shoot, without auricles and with a prominent white midvein; toothed, membranous ligules; leaf blades usually have no hairs on both surfaces, but may be present at the base of the leaf blade.
- Seedhead: Large, purplish tinted, open panicle that develop during the summer months. Seeds are dark red to black at maturity, oval-shaped, 3 - 5 mm in length.
- Look alikes: Barnyardgrass (Echinochloa crus-galli)) and/or Fall panicum (Panicum dichotomiflorum) prior to seedhead formation.
Johnsongrass can often cross with other Sorghum
species, which results in plants which are difficult to identify accurately. Johnsongrass has adapted to a wide variety of habitats including open forests, old ﬁelds, ditches and stream banks.
Johnsongrass has the capability of producing high levels of cyanogenic glycosides and nitrates, which can be lethal to horses if ingested.