The Tallgrass Prairie in Illinois
Images of Prairie Plants
The Illinois Plant Information Network (ILPIN), located at the Illinois Natural History Survey, is a computerized data base listing life-history, habitat, taxonomic and geographic distribution information available for the vascular flora of Illinois. The ILPIN data base records 851 species of plants native to Illinois prairies. Examining the diversity of Illinois prairies by county shows that this diversity differs from region to region. The Chicago region, with its large diversity of prairie types, contains many plant species. Many species also occur along the Mississippi and Illinois rivers. Somewhat surprising is the large number of prairie species in extreme southern Illinois, occurring in the numerous small prairie openings in this part of the state.
This level of plant diversity, however, is not found on any single prairie. A general pattern of increasing diversity with size of a habitat patch is commonly observed across a wide range of taxonomic groups and habitat types. Patches larger than 10 acres contain most of the local diversity of plants, approximately 100-120 species. Unfortunately, fewer than 17% of all remaining prairies in Illinois are above this size threshold. Nevertheless, a substantial amount of floristic diversity is preserved in small habitat patches.
While the number of species of prairie plants found in prairies is rather low compared to the number of forest and woodland species, the species diversity within a given prairie can be quite high, and over 100 species can occur in an area of less than 5 acres. Not all species of plants are noticeable at one given period of time, rather there is a progression of species throughout the growing season.
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A Brief Introduction to the Terminology of Flowering Plants
For a much more complete introduction to the structure and terminology used in flowering plants, see Digital Flowers, the courseware used in the Plant Systematics (Taxonomy) class at the University of Illinois.