GEOLOGIC HISTORY OF THE LOCUST 289 



Pliocene times. A well marked locust has also been found in 

 the deposits of the lake basin at Florissant, Colorado, but no 

 other North American Miocene form has been discovered. 



In addition to the very modern looking Pliocene form already 

 mentioned a second was common at this time along the Medi- 

 terranean coast of southern Europe from Spain to Slavonia. 

 There is no evidence that the locust survived the first glaciation 

 in Europe but in North America we find the modern species in 

 the Interglacial deposits of the Don valley in Ontario some 

 distance north of its existing range, and it is also found in the 

 late Pleistocene of Maryland. 



THE HONEY LOCUST (Gledilsia) 



This black locust is sometmies called the honey locust in New 

 England because of its fragrant nectar-bearing blossoms. The 

 true hone}^ locust is, however, quite another tree and belongs 

 to the famil}^ Caesalpiniacea?, Robi7iia belonging to the family 

 Papilionacese. 



The honey locust belongs to the genus Gleditsia, sometimes 

 spelled Gleditschia since it was named by Linnaeus in 1753 in 

 honor of J. T. Gleditsch, a german botanist. Gleditsia contains 

 five or six species natives of eastern North America and Asia, 

 and three of these are found in the United States. One, Gle- 

 ditsia texana Sargent, is confined to the Brazos River valley in 

 Texas; a second, the water locust Gleditsia aquatica Marsh, is 

 found in our southern states: and the true honey locust, Gle- 

 ditsia triacanthos Linnaeus, a tall graceful tree, ranges from 

 Ontario and western New York to Georgia, Kansas and Texas. 



The honey locust is a large tree 75 to 140 feet in height and 

 with a trunk two or three and occasionally as much as six feet 

 in diameter. It is exceedingly graceful in habit with its slender 

 spreading and somewhat pendulous branches fomiing a broad 

 open head. This together with its tiny leaflets gives it more 

 the appearance of so many of the tropical species of Leguminosa? 

 rather than of a tree of the Temperate Zone, and it is conse- 

 quently a general favorite as an ornamental and shade tree in all 

 countries with a suitable climate. 



