Plant Migration Studies 13 



Cherries and Plnms { Pniniis spp.). The monocarpellary, two- 

 ovuled ovary becomes a fleshy one-seeded drupe. The hard shell 

 of the stone protects the seed from crushing when the fruit is 

 eaten by birds or quadrupeds, and preserves many of the em- 

 bryos while the seeds are passing through the alimentary canal. 

 The smaller fruits (cherries) are greedily eaten by many birds, 

 while the larger (plums) are eaten by quadrupeds, and occa- 

 sionally carried away by birds. 



Choke Cherry (Prnnus zirginiana L.) is found in the Mis- 

 souri forests, from which it has been carried northward along 

 the Missouri River as far as Sarpy County, and westward in the 

 Nemaha, Blue and Republican river vallevs to Franklin County 



(31). 



Wild Black Cherry (Pruniis scrotina Ehrh.) occurs in the for- 

 ests of Missouri, from wdiich it has spread into southern and 

 eastern Nebraska, to Sarpy County along the Missouri River, 

 and Franklin County in the valley of the Republican River (32). 



Wild Plum (Priuins anicricana Marsh.) is common in the 

 country East of the Plains, into and across which it appears to 

 have been carried, so that it is now found in the Rocky Mountain 

 region. It is found in all parts of Nebraska (33), even in the 

 "pockets" in the Sandhills into which it must have been carried 

 by birds. 



Kentucky Coffee Tree (Gyninocladiis dioica (L.) Koch). The 

 large monocarpellary fruits (15-18 centimetres long, 4-5 wide, 

 and nearly 2 centimetres thick) contain about half a dozen large, 

 spherical, very hard seeds, imbedded in a sweet pulp. The ri- 

 pened pods hang on the trees for a part of the winter, and when 

 they fall are picked up by quadrupeds which are attracted by 

 their sweet odor. The hardness of the seeds prevents their be- 

 ing crushed. The tree occurs in the Missouri forests, and b.as 

 followed the Missouri and Niobrara rivers northwestward to 

 Rock county (34). In the southeastern part of the state it has 

 followed the smaller streams westward fifty to sixty miles from 

 the Missouri River. 



Honey Locust (Gicditsia triacanthos L.). The large twisted 

 and bent monocarpellary fruits (20-30 centimetres long, 2-2.5 



23 



