THE GENERAL CHARACTERS OF SEEDS 



487 



inconspicuous scar of nearly the same color as the rest of the 

 achene. 



Sunflower (Helianthus annuus L.). 



Achenes obovate, oblong, somewhat flattened, one-fifth to one- 

 quarter of an inch long; with appressed pubescence (see figure) 

 especially at upper end, grayish and mottled with brown ; marked 

 by longitudinal lines; more prominent ridge in center; lower end 

 of achene notched, containing the scar; the apical scar with a 

 slightly elevated circular margin ; cotyledons large and fleshy. The 

 achenes, according to Mr. Fracker, are long, slender, and duplex; 

 H. tuberosum has simple and several-celled trichomes but not duplex. 

 H. occidentalis has short, thick, duplex hairs. 



Pig. 361A Fig. 361B Fig. 361C Fig. 361D 



Pig. 361. Seeds of Cone-flower and Sunflower. A. Coneflower {Lepachys pin* 

 nata). B and C. Common Sunflower {Helianthus annuus). D. Meadow 

 Sunflower {Helianthus grosse-serratus) . 



(A, drawing by Ada Hayden ; B and D, drawings by C. M. King ; C, after 

 Hillman, Bull. Mich. Exp. Sta.) 



Saw-toothed Sunflower (Helianthus grosse-serratus Martens). 



Achenes oblong, narrowed at base and broad at apex, flattened, 

 with 2 edges, and 1 prominent ridge, sometimes 2 on each side; 

 one-sixth to one-fifth in. long ; pappus of 2 lanceolate awns ; smooth 

 or slightly hairy; brownish or lighter color, mottled with brown; 

 the scar at the end is in the form of a small notch; the remnant 

 of a corolla tube at the apex; cotyledons fleshy. 



Prairie Sunflower (Helianthus petiolaris Nutt.). 



Achenes obovate-oblong, but slightly flattened, villous pubescent, 

 (see figure), a prominent longitudinal ridge and several lines on 

 each side ; grayish, mottled with brown ; scar in notch at the lower 

 end; scar on upper end circular; cotyledons 2, large and fleshy. 

 According to Mr. Fracker, the achenial hairs are long and slender 

 and duplex. 



