THE GENERAL CHARACTERS OF SEEDS 



453 



IffC 



A A B 



Fig. 308. Bur Clover (Medicago hispida). A, seed; B, pod. 

 (Drawings by Ada Hayden and L. R. Collins.) 



Yellow Trefoil (Medicago lupulina L.). 



Seeds kidney to egg-shaped, much shorter than bur clover seed, 

 one-twelfth to one-tenth in. long; about the size of alfalfa, which 

 it closely resembles ; color yellowish, reddish, or greenish ; scar near 



Fig. 309. Yellow Trefoil (Medicago lupulina). A, seeds showing the prevail- 

 ing forms. B, pods ; the central one with the calyx removed ; the one at 

 the left an immature, lighter colored specimen. C, a view of a seed in cross 

 section, showing cotyledons and caulicle. D, the embryo. E, seeds and 

 pods, natural size. 



(After Hillman, Bull. Nev. Agr. Exp. Sta.) 



one end; micropilar processes prominent; the pods clustered at the 

 end of the peduncle small, black, wrinkled, and coiled at tip, marked 

 by prominent veins and hairs; each pod contains one seed. 



Dalea (Dalea alopecuroides Willd.). 



Seeds triangular to kidney-shaped, one-tenth in. in length ; mi- 

 cropilar scar prominent, with whitish border and 2 micropilar 

 processes; surface shining, slate-colored. Found in clover seed, 

 from which it is separated with difficulty. 



