THE GENERAL CHARACTERS OF SEEDS 



499 



Dandelion (Taraxacum officinale Weber). 



Achenes two-fifths in. long including persistent beak, fusiform in 

 shape, prominent ribs, and projecting teeth at ribs, especially at 

 upper end ; beak four-fifths to one in. in length ; achenes light gray in 

 color, otherwise like preceding; pappus capillary, whitish, fragile. 

 With grass seeds. 



Field Sow Thistle (Sonchus arvensis Ik). 

 Achenes dark reddish brown, dull, ends slightly truncate, length 

 2.5-3 mm., width 0.8 mm., somewhat flattened, with 4 strong ribs or 

 angles, between which lie smaller ridges ; numerous transverse ridges 

 on the ribs. 



6 A 



Pig. 378C 



Fig. 378. Seeds of Sow Thistles. A. F.ield or Perennial Sow Thistle (Sonchu3 



arvensis) ; B, natural size, showing pappus on one achene. 



B. Sonchus oleraceus, different views of achenes. 



C. Sonchus asper, A and B, different views of achenes, C, achenes, natural size. 



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



Spiny Sow Thistle (Sonchus asper Vill.). 



Achenes broadly oblong or lance-shaped, similar faces, many- 

 ribbed, one-tenth in. long, slightly pubescent, prominent ridges 

 minutely roughened ; base with a minute scar, brownish ; the apex 

 with projecting point and fine, capillary, white, bristles. Found 

 with grass seeds. 



