Wildflowers 



of the Chicago Area 



Late Summer and Autumn 



byFloydA.Swink 



photos courtesy of the author except where indicated 



In the temperate zone there are two basic times for 

 increased interest in wildflowers. One is the spring 

 (treated in the April Bulletin), and the other is late 

 summer and autumn. Reasons for this include cool 

 weather, lack of mosquitoes, and return to school, and 

 thus reductions in vacations away from home. 



It may be surprising to learn that many more flowers 

 in the Chicago area can be seen in bloom on Labor Day 

 than on any peak day in spring. In fact, the Chicago area 

 has 27 species of asters and 21 species of goldenrods — 

 seeing these 48 species alone would make quite a day's 

 field trip. These belong to the Composite Family, and 

 members of that family are purposely treated first here in 

 order to give some idea of the wealth of floristic beauty 

 contained in this large family. 



Blazing Star (Liatris aspera) 



Gay Feather (Liatris pycnostachya) 



$? Blazing Star (Liatris aspera) 

 Composite Family (Compositae) 



This is found on dry prairie and is also very common in 

 the sand regions. The common names in Liatris overlap, 

 but generally the blazing stars have large flower heads 

 which occur somewhat separately, while the gay feathers 

 have dense spikes. Examination with a hand lens reveals 

 a beautiful display of tiny disk florets compacted together 

 into a head. It is one of the best plants to exhibit the fact 

 that the flower head is not really a single flower, but 

 rather a "composite" of a number of small flowers. 



"$? Gay Feather (Liatris pycnostachya) 

 Composite Family (Compositae) 



This beautiful flower is often sold as an ornamental by 

 florists. The genus Liatris is very unusual in that it is one 

 of the very few plants in which the floral spike has the 

 oldest flowers at the top rather than at the bottom. This 

 is a fine prairie plant; its close relative, Liatris spicata, 

 equally beautiful, is often found in moist habitats. 



$? Bur Marigold (Bidens coronata) 

 Composite Family (Compositae) 



The combination of heavily disturbed areas in our sub- 

 urbs, together with a flat substrate above a clay soil 

 which is near the surface, gives opportunity for this and 

 closely related species to grow almost to the exclusion of 

 everything else. The bur marigolds are often mistaken 

 for sunflowers, but actually they are "stick-tights." These 

 are the plants with flat seedlike fruits which have two or 

 more points at the tip. The two-pointed ones look like 



Floyd A. Swink is a taxonomist at Morton Arboretum, Lisle, Illinois, and 

 has served as lecturer and tour leader of Field Museum botanica! trips in the 

 Chicago area. His article "Spring Wildflowers of the Chicago Area" 

 appeared in the April 1986 Bulletin. Mr. Swank is co-author (with 

 Gerould Wilhelm) of Plants of the Chicago Region, 3rd ed. , 922 pp. , 

 published by Morton Arboretum. 



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