THE GENERAL, CHARACTERS OF SEED'S 



497 



Fig. 375A Fig. 375B Fig. 375C 



Fig. 375. Seeds of Corn-flower and Knapweed. A. Barnaby's Thistle or 

 Knapweed (Centaurea solstitialis) ; a, achene with pappus, c, pappus re- 

 moved, b and d, achenes, natural size. 

 B. Corn-flower (.Centaurea cyanus). C. Achenial hairs of Corn-flower. 



(A, after Hillman, Bull. Nev. Agr. Exp. Sta. ; B, after Nobbe ; C, drawing by 



S. B. Fracker.) 



Bristly Ox-tongue (Picris echioides L.). 



Achene elliptical, narrowed at base, with projection at tip ; one- 

 tenth in. in length ; light brownish red ; wrinkled transversely, espe- 

 cially toward apical end. Found in seed of alfalfa and clover. 



Oyster Plant, Salsify (Tragopogon porrifolius L.). 



Achenes linear, terete, beaked or long, covered with scalelike 

 tubercles on the ribs, or merely roughened, light straw-colored or 

 darker pappus of numerous plumose bristles; small scar at apex, 

 whitish with a depression scar at base with an oval depression. 

 Reported as a "weed of alfalfa meadows." 



Meadow Salsify ( Tragopogon pratensis L. ) . 



Achenes linear, terete, one-half in. or little more long, exclusive 

 of beak; scar at base, whitish, with an oval depression; beak one- 

 third in. long; scar at end of beak whitish, with a depression, 

 striate, smooth or slightly roughened, light straw-colored or darker ; 

 pappus of numerous soft, brownish, plumose bristles. 

 32 



