This volume contains four orders and ten families of dicots. The orders included are Malvales, Urticales, Rhamnales, and Euphorbiales. Within the Malvales are the families Tiliaceae, Sterculiaceae, and Malvaceae. The families Ulmaceae, Moraceae, and Urticaceae comprise the Urticales. The Rhamnaceae and Elaeagnaceae make up the Rhamnales. Only the Thymelaeaceae and the Euphoribiaceae are included in the Euphorbiales.
The nomenclature for the species and lesser taxa used in this volume has been arrived at after lengthy study of recent floras and monographs. Synonyms, with complete author citation, that have applied to species in the northestern United States are given under each species. A description, while not necessarily intended to be complete, covers the more important features of the species.
The common name, or names, is the one used locally in Illinois. The habitat designation is not always the habitat throughout the range of the species, but only in Illinois. The overall range for each species is given from the northeastern to the northwestern extremities, south to the southwestern limit, then east to the southeastern limit.
The range has been compiled from various sources, including examination of herbarium material and some field studies. A general statement is given concerning the range of each species in Illinois. Dot maps showing county distribution for each taxon are provided. Each dot represents a voucher specimen deposited in some herbarium. There has been no attempt to locate each dot with reference to the actual locality within each county.
Each species is illustrated, showing the habitat as well as some of the distinguished features. These detailed illustrations were provided by Mark Mohlenbrock.