Johnson Grass, Sorghum halepense, is an invasive, warm season grass. It can be found in disturbed habitats in central and southern Illinois, and it can often be found in large patches since it spreads through rhizomes. This grass can grow four to seven feet tall. It has thick, glaucous stems, meaning they produce a white bloom like a sunscreen that can be wiped off. The leaves are broad and several feet long with a prominent white midrib, and they're wrapped really tightly around the stem. But when you do pull the leaf blade back you'll find a ligule of velvety hairs.
Johnson Grass produces a panicle inflorescence that can be over a foot tall. Its spikelets, some of which have awns, can be found along branches. If you catch it in bloom, you can see white to pink stigmas and yellow to brown anthers pushed out of the spikelets.
This video is part of the Grasses at a Glance series by Natural Resources, Environment, and Energy Educator Erin Garrett, University of Illinois Extension. Explore the playlist. Read our blog Grasses at a Glance.