Since the publication of the first edition of Grasses: Panicum to Danthonia in 1973, twenty additional taxa of grasses have been discovered in Illinois that are properly placed in this volume. In addition, numerous nomenclatural changes have occurred for plants already known from the state, and many distributional records have been added. This second edition updates the status of grasses in Illinois. Paul W. Nelson has provided illustrations for all of the additions.

Because the nature of grass structures is generally so different from that of other flowering plants, a special terminology is applied to them. In his introduction, Robert H. Mohlenbrock cites these terms, with descriptions that make the identification of unknown specimens possible. Mohlenbrock’s division of the grass family into subfamilies and tribes is a major departure from the sequence usually found in most floristic works in North America.

Synonyms that have been applied to species in the northeastern United States are given under each species. A description based primarily on Illinois material covers the more important features of the species. The common names—Paflic Grass, Billion Dollar Grass or Japanese Millett, Thread Love Grass, and Goose Grass—are the ones used locally in the state. The habitat designation and dot maps showing county distribution of each grass are provided only for grasses in Illinois, but the overall range for each species is also given.