488 WHITE— STUDIES OF INHERITANCE IN PISUM. 



P. fulvuni Sibth. — Asia Minor, Syria. 

 P. humile Boiss. — Syria, Palestine. 

 P. Jomardi Schrank. — Egypt. 

 P. sativum Linn. — Europe, Asia. 



P. arvensc, P. elathis, and P. Jomardi, as grown from seed ob- 

 tained through the Foreign Seed and Plant Introduction division of 

 the U. S. Department of Agriculture, from various botanic gardens, 

 seedsmen and other sources, are very similar, all having colored 

 flov^^ers, colored seed coats and a similar habit of growth. All three 

 species when crossed produce fertile hybrids. Many students con- 

 sider the differences between P. sativum and P. arvense not marked 

 enough to warrant calling them by distinct specific names. Such 

 students regard P. arvense as a sub-species of P. sativum. The 

 purple-seeded Abyssinian pea is a very distinct form of P. sativum 

 or P. sat. arvense, differing strikingly in seed and leaf characters 

 from all other forms of this species. P. formosum is a perennial 

 alpine form, lacking tendrils and very distinct as regards general 

 habit and seed characters. P. fiilvum has rusty cream-colored flow- 

 ers and seeds with black seed coats. P. humile, though resembling 

 small-leaved forms of P. arvense, gives partly sterile hybrids in 

 crosses with the latter. Experimental work embraced by this re- 

 view deals largely with forms of P. arvense, P. sativum and P. 

 elatius, of which there are at least some five hundred varieties 

 known. 



About 250 of these varieties have been grown for three years 

 in the experimental breeding plots of the Brooklyn Botanic Garden, 

 where many of the experiments described in succeeding pages have 

 been repeated and confirmed. Most of the descriptions of Pisum 

 characters in the following pages are based on notes on these varie- 

 ties. For help in bringing together this collection, which includes 

 forms from all over the world, I am indebted especially to the Offi- 

 ces of Foreign Seed and Plant Introduction and Forage Crop In- 

 vestigations of the U. S. Department of Agriculture, Arthur Sutton 

 of Sutton & Sons, P. de Vilmorin, Haage & Schmidt, W. Bateson, 

 C. Pellew, A. D. Darbishire and various botanic gardens of Europe 

 and Asia. 



As a whole, the differential characters of these species are sur- 



