177 



about ore mines while other more aggressive species fail even to es- 

 tablish themselves. 



The members of this family are distinctly characterized by their 

 fruit which matures in one season and usually resembles ordinary 

 garden beans or peas. The fruit of some of the trees found in the 

 western part of North America varies more or less from the typical 

 bean-like fruit pod. The flowers of our native trees may be irregular 

 in form, i. e. pea-like or bean-like, as in the Common Locust and Ked- 

 bud, or regular in form as in the Honey Locust and Kentucky Coffee 

 Tree. The two native tree-species with irregular flowers have also 

 perfect flowers, i. e. flowers with both the male (pollen producing) 

 and female (seed producing) organs in the same flower while the 

 other two native tree-species have regular but imperfect flowers, i. 

 e. flowers with one sex so suppressed that only the other sex remains 

 in each flower. Whenever the male and female flowers, also known 

 as staminate and pistillate flowers respectively, occur separately, 

 they may be found on the same branch, or on the same tree, or on 

 different trees. The leaves of nearly all the tree members of this 

 family are alternate and compound, but a few such as our native 

 Kedbud have simple leaves. Some species as our Common Locust are 

 normally only once compound, others as the Honey Locust may be 

 once or twice compound, while still others, as the Kentucky Coffee 

 Tree, may be normally twice compound. 



SUMMER KEY TO THE GENERA. 



Page. 



1. Leaves simple; Lwigj slender and unarmed Cercis 180 



1. Leaves compound; twigs stout or armed with spines or tborns, 2 



2. Twigs very stout aud clumsy but not armed with spines or thorns; fruit-pods woody; 



leaves twice compound, from 1-3 ft. long, Gymnocladus 178 



2. Twigs relatively slender and armed with spines or thorns; fruit-pods leathery; leaves 



usually cnce or sometimes twice compound, rarely over 1 ft. long, 3 



3. Flowers greenish, regular or nearly so, imperfect, in axillary spikes; leaves once 



or twice compound, even-pinnate; twigs, branches, and often trunks with long 



branched thoru.s Gleditsia 179 



3. Flowers whitish, irregular, perfect in drooping racemes; leaves usually once com- 

 pound, odd-pinnate; twigs often with two short spines at nodes, Robinia 181 



WINTER KEY TO THE GENERA. 



1. Twigs, branches, and trunks usually armed with spines or thorns 2 



1. Twigs, branches, and trunks without spines or thorns, 3 



2. Twigs and branches armed with a pair of spines not exceeding i of an inch in 



length at each node; fruit-pods 2-4 inches long, J of an inch broad; bark reddish- 

 brown, even on young trunks deeply furrowed, Robinia 181 



2. Twigs, branches, and often trunks usually ermed with thorns which occur singly, 



are often branched and usually much exceed h of an inch in length; fruit-pods 10-18 

 inches long, 1-1^ inches wide; bark ijrayish-brown to black, not furrowed, often 

 covered with conspicuous oblong lenticels, Gleditsia 179 



3. Twigs stout, clumsy, blunt-pointed, with large conspicuou.s bundle-scars and large 



pink to brown pith; fruit-pods thick, woody, stubby, contain fleshy pulp and large 

 seeds; buds silky-pubescent, depressed, uppermost one surrounded by incurved 



hairy ring of bark, Gymnocladus 178 



3. Twigs slender, not clumsy nor blunt-pointed, with inconspicuous bundle-scars and 

 pith with reddish longitudinal streaks; fruit-pods very thin, leathery, without 

 fleshy pulp, an.l contain small seeds; buds smooth, not depressed, often somewhat 

 flattened and appressed Cercis 180 



12 



