Sorghum halepense

It is an erect, 2½ to 6-foot tall, coarse, herbaceous perennial grass in the Poaceae family thought to be native to the Mediterranean area but is now found in all temperate areas of the world. It was introduced in South Carolina from Turkey around 1830 by William Johnson and planted along the Alabama river as a forage plant. However, it is crucial to note that mature Johnson grass can contain high levels of hydrocyanic acid (also known as prussic acid), making it poisonous to livestock if they consume it, especially during periods of stress like drought. Johnsongrass is identified by its thick, smooth stems with a whitish bloom, long leaves with a prominent white midrib that snaps when folded, and a large, purplish, pyramidal seed head. It also has thick, fleshy underground stems (rhizomes) that allow it to spread aggressively, forming dense clumps.