GEOLOGIC HISTORY OF THE LOCUST 285 



but a few and these are found in the cabinet maker's rather than 

 in the kunber trade, and scarcely any awaken a concept in the 

 popular mind unless it be rosewood (Dalbergia), a tree of the pea 

 famih' which furnishes such an incomparably handsome cabinet 

 wood. 



There are about 500 genera and 10,000 existing species of 

 Leguminosse, of which only 17 genera with about 32 species 

 attain to the stature of trees within the limits of the United 

 States, and the bulk of these are confined either to the sub- 

 tropical coastal belt of Florida or to the arid southwest. The 

 only tree forms that are widely familiar in the eastern states 

 are the Judas-tree or Red bud (Ceixis), the Kentucky coffee tree 

 (Gymnocladus) , and the honey locust {Gleditsia) of the family 

 Caesalpiniaceae and the locust (Rohinia) of the family Papilio- 

 nacese, so that our attention in the present article will be confined 

 to these four trees. 



THE LOCUST {Rohinia) 



The black locust, often called the yellow locust because of its 

 yellowish brown heart wood and yellowish white sapwood, is the 

 type of the genus Rohinia, so named by Linnaeus in honor of 

 Jean and Vespasian Robin who introduced it into Europe at the 

 end of the sixteenth century, at which time the fornier was in 

 charge of the Garden of the Louvre. The specific name which 

 Linnaeus gave this species, pseudacacia, commemorates in 

 latinized form the common European name of false acacia by 

 which this North American tree has usually been known abroad. 



Its natural range extends from Pennsylvania to Georgia and 

 westward to Iowa but it has been extensively naturalized on our 

 western prairies as well as on the plains of Hungary. Perhaps 

 no American tree was so extensively planted in Europe, and our 

 colonists also, in the period immediately following the Revo- 

 lution, valued it highly both for its timber and for its beneficial 

 effect upon soils. In Revolutionary France May 6 was conse- 

 crated to the locust. 



It is a medium sized tree and, while it sometmies reaches a 

 height of 90 feet and a trunk diameter of 4 feet, the average tree 



