Many people are under the impression that the Chicago region is a comparatively poor place to study plant life due to its great industrial expansion, with the resulting decimation of many native species. While there has been a diminution of many such species, the actual number of species has increased during the last century. A complete check list taken at the present time would indicate about 1,900 species of flowering plants in the Chicago region,considering that that area should embrace the Indiana dune region and the new state park north of Waukegan, and going as far west as the Fox River.
Let us consider an area of approximately equal size in the Rocky Mountains of Colorado - a region long noted for its botanical possibilities. In this area we can include the Rocky Mountain National Park, and a territory of about equal size, completely surrounding the park. In this region are found less than 1,000 kinds of flowering plants in an area just as large as Chicago and vicinity. Let us analyze 2 basic reasons for this difference in figures.
First, Chicago is the world's greatest railroad center. A number of plants native to the vast Great Plains region have, therefore, been distributed by trains and have found very suitable habitats in our territory. Impure lawn seed accounts for a goodly number of introductions. There are many activities of man, in altering the earth's surface, which are considered to be directly responsible for other introduced species. On the other hand, the Rocky Mountain region above mentioned is relatively little disturbed, and there is much less opportunity for plant introductions.
Secondly, Chicago is located at the critical junction of several well-marked botanical areas. It is at the eastern terminus of the noted prairies of the Midwest, and is at the western edge of the beech-maple type of forest of the Eastern states. Also, it is near the southern tip of the sphagnum bog type of habitat so common in the North Woods and Canada, and which contain so many interesting plants of the heath and orchid families. Coupled with this, the location of a portion of this area at the southern tip of Lake Michigan has resulted in the formation of a remarkable series of sand dunes, which support a flora uniquely different from other Midwestern areas.
In contrast to these factors, the Rocky Mountain region of which we speak is located in only one general botanical area -- that of the coniferous forest. The factor of altitude, however, divides this region botanically into the montane, sub-alpine, and alpine zones, which accounts for a greater variety of plant life, but does not add as many species as might be imagined.
In conclusion, therefore, let us not feel that we must leave home, and visit some foreign country or a national park to secure the desired diversity in plant life. There is enough here to keep anyone busy -- and plenty more. All we need to do is get out into the field, and keep our eyes open.