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CommentsIn Illinois, Johnson Grass can become quite large in size and it has a tendency to stand out from the surrounding vegetation. In spite of its weedy character, this grass is rather attractive while it is in bloom. The foliage of Johnson Grass has a similar appearance to the foliage of Tripsacum dactyloides (Gama Grass). For example, their leaf blades are quite long and broad, shiny green, and pale-striped from their prominent central veins. However, the inflorescence of Johnson Grass is quite different from the inflorescence of Gama Grass. The latter species has a cluster of stout floral spikes, while Johnson Grass has a spreading panicle of florets with slender branchlets. Another species, Sorghum bicolor (Sorghum), is occasionally cultivated as an agricultural crop. Sorghum is an annual and its inflorescence is more dense and upright in appearance than the inflorescence of Johnson Grass. Another annual species, Sorghum almum (Columbus Grass), has been introduced into the United States from Argentina. This species resembles Johnson Grass, but it is even larger in size with leaf blades typically 1-2' across. Columbus Grass is restricted to southern Illinois, where it is rare.