THE GENERAL CHARACTERS OP SEEDS 441 



Prickly Poppy {Arg&mone intermedia Sweet). 



Pod ellipsoid, prickly; seeds spherical, crested, about 2 mm. in 

 diameter; dark brown, surface reticulate and deeply pitted. 



CRUCIFERAE, MUSTARD FAMILY. 

 Pennycress {Thldspi arve')ise L.). 



Seed oblong, flattened, one-twelftb to one-tenth in. long; sur- 

 face marked by curved ridges, simple or occasionally forked, which 

 curve from base to apex in regular rows; color brownish to dark 

 reddish brown; funicle sharp pointed. Found largely in wheat, 

 barley and o'a,ts. "A pest of grain (wheat) fields of Manitoba." 



Fig. 287. 



Figure 287A 



Figure 287B 



A. Pennycress (TMasvi arvense). A, side view of a seed; B, 

 natural size ; C, the embryo. 

 B. Cress {Lepidvuin sativum). 

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



seeds, 



Cress {Lepidium sativum L.). 



Seed oval, one edge nearly straight, the other convex, one-tenth 

 in. in length, apparently slightly marginate at basal end, basal 

 portion bearing scar, also with white projecting 'tip, and end of 

 funicle prominent, smooth, brownish. 



Small Peppergrass {Lepidium apetalum Willd.). 



Seeds oblong, flattened, margin colorless, prominent ridge on 

 one side, one-sixteenth to one-twelfth in. long, minutely rough- 

 ened ; cotyledons incumbent ; seed coat becomes mucilaginous when 

 wet; funicle prominent. Generally found in small grains and 

 commercial grass seed. 



