RUBIACEAE 



251 



flowers each; and the heads may be either terminal or lateral 

 but in any case situated toward the end of the twigs and fre- 

 quently beyond the last leaves. The small, creamy white, mostly 

 4-parted flowers blossom from early in July until early in 



FIG. 66 

 Cephalanthus occidentalis 



September. Fruit matures in the autumn, forming globose 

 heads composed of numerous pyramid-shaped capsules generally 

 about 14 i^ch long. 



Distribution. — The Buttonbush inhabits margins of swamps, 

 ponds and sloughs from New Brunswick to southern Minnesota 

 and south to Florida and Texas. In Illinois, it is statewide in 

 distribution and increases both in abundance and size from 

 north to south, being rarely abundant in running water but 

 extremely common wherever water is still. In many situations 

 it invades the margins of ponds, and in southern Illinois often 

 is the principal shrub on the edges of the backwaters of the 

 large rivers. 



A variety, pubescens Rafinesque, is distinguished on the basis 

 that branchlets, peduncles, petioles and the entire under surface 

 of the leaf are pubescent. This form is probably coextensive 

 with the rest of this species in Illinois. 



