144 LEGUMINOSAE 



corner. Southward it becomes rare, and has not been reported 

 south of Jefferson and St. Clair counties. 



Forms of this cherry which occur in the northeastern part of 

 the state, especially on the sand near Lake Michigan, are re- 

 ferred to the variety demissa (Nuttall) Torrey, which differs 

 in having the underside of the leaves woolly-pubescent and the 

 leaf blades more or less cordate at the base. Also, the branch- 

 lets are puberulent and the rachis and pedicels of the inflores- 

 cence are pubescent. 



LEGUMINOSAE 

 The Pea Family 



The pea family includes herbs, vines, shrubs and trees, all of 

 which bear alternate and for the most part compound, stipulate 

 leaves and irregular but mostly perfect flowers in spikes, heads, 

 racemes or panicles. The calyx in this family is 4- to 5-toothed 

 or 4- to 5-cleft, the lobes being either equal or unequal and 

 sometimes 2-lipped. The petals are more or less united and 

 usually consist of a broad upper one, called the standard or 

 banner, 2 lateral ones, known as w^ngs, and 2 front ones which 

 are more or less united to form the keel. The stamens may be 

 monodelphous, diadelphous or sometimes separate. In most 

 genera there are 10; sometimes there are 9, and rarely there are 

 only 5. The pistil is simple and generally there is only 1 per 

 flower. The ovary is superior and for the most part 1-celled, and 

 the style is simple and unbranched. The fruit, commonly known 

 as a legume, is a 1- to many-seeded pod which opens by 2 valves. 



There are over 300 genera and more than 10,000 species in 

 this family. They are most abundant in temperate and warm 

 regions and include a large number of commercially important 

 plants. Although many species of herbs and several trees na- 

 tive in Illinois belong to this family, only two of the native 

 genera are represented by shrubby species. These shrubs are all 

 plants of special habitats, and each occurs only where favorable 

 habitats exist in the state. The local variation in characteristics 

 has given rise to varietal names not recognized below^ 



Key to the Shrubby Genera 



Upright shrubs with glandular-punctate leaves. . Amorpha, p. 145 

 Twining vines; leaves not glandular-punctate Wisteria, p. 146 



