THE GENERAL CHARACTERS OF SEEDS 



481 



Willow-leaved Aster (Aster salicifolius Ait.). 



Achene slender, pale brown, about 1.5 mm. long and .25 mm. 

 broad ; 5 longitudinal ribs at angles of seed ; pappus straw-colored, 

 hairs or bristles 6 mm. in length. The achenial trichomes are long, 

 the duplex character very pronounced, according to Mr. Fracker. 



Fig. 353A Pig. 353B Fig. 353C 



Fig. 353. Seeds of Aster, Whiteweed and Horseweed. 



Fig. 353D 

 A, Aster salicifolius. B, 



Daisy Fleabane or Whiteweed (Erigeron annuus). C, Horseweed (.Erigeron 

 canadensis). D, Whiteweed (Erigeron ramosus). 

 (A and B, drawings by Charlotte M. King ; C and D, after Hillman ; C, Bull. 

 Nev. Agr. Exp. Sta.; D, Bull. Mich. Exp. Sta.) 



He found much variation in the trichomes of the genus. The hairs 

 of A. drummondii are shorter. The trichomes of A. tradescanti 

 and A. macrophyllus are longer and more slender than in A. drumi- 

 mondii. The duplex hairs of Aster laevis, A. oblongifolius, A. novae- 

 angliae and A. multiflorus are slender. 



Fig. 354C 



Fig. 354D 



Fig. 354A Fig. 354B 



Fig. 354. Achenial hairs of Asters. A. 

 salicifolius. C. Aster tradescanti. D. 

 multiflorus. 



(Drawings by Mary A. Nichols and S. B. Fracker.) 

 31 



Aster novae-angliae. 

 Aster oblongifolius. 



B. 



E. 



Fig. 354E 



Aster 

 Aster 



