888 



]\Iiss()uri Af/nniJfiiral Frporl. 



TESTING VETCH SEED. 



A popular test of vetch seed consists chiefly in distinguishing the 

 seed of hairy (winter) vetch and that of spring vetch, and determining 

 the viability. 



Winter vetch seed (fig. 32, a) consists of nearly spherical, steel- 

 black seeds showing some variation in size. The seed is distinguished 

 from other kinds by its characteristic seed-scar which is oblong-oval with 

 a whitish slit through the center. A small protuberance (the chalaza) 

 of the seed coat is located nearly the length of the scar distant from the 

 narrow^er end of the scar, as shown in the figure. 



Seeds of spring vetch represent several varieties and thus are vari- 

 able in size, form and surface. The characteristic scar is wedge-shaped 

 with a slender, black slit through its center, the slightly raised margins 

 of the slit usually being light -colored. The usually distinct chalaza, as a 

 rule, is al)out half the length of the scar distant from the narrower end of 

 the scar (fig. 32, b). Some seeds of spring vetch are large, compressed, 

 and somewhat angular; others are nearly spherical and smaller. The 

 surface is black, brown, gray or mottled. In one variety, a common im- 

 purity of winter vetch seed, the seeds are spherical, jet-black and about 

 the size of the smaller winter veteh seeds. Only careful examination un- 

 der a magnifier discloses their daiker color and characteristic scar, in 



Fig. 32. — Seeds of three kinds of vetr-h : a, Wintei- (or hairy) vetch; 1». sprinpr 

 vetch; c, wild vetch {Vicia hirsitta). (Enlarged and natural size.) 



which, however, the margins of the scar slit are black. In testing seed 

 of winter vetch the seeds of this variety of spring vetch should be sought 

 especially. Seeds of other varieties of spring vetch are usually distin- 

 guishable from winter vetch seeds by their different form or color. 



Various weed seeds, mostly of the class appearing in seed of millets 

 and cereal grains, are sometimes present in poorly cleaned vetch seed. 

 The seed of a wild species of vetch ( Vicia hirsnfa (L.) Koch, fig. 32, c) 

 is a common impurity of cultivated vetch seed. 



Vetch seed should show nearly 100 i^er cent purity. The viability 

 of commercial seed is variable and is strongly influenced by the hard 



