THE GENERAL CHARACTERS OF SEEDS 



481 



Willow-leaved Aster {Aster saUdf alius 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 aehenial trichomes are long, 

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



Fig. 353A . Pig. 353B Fig. 3530 Fig. 353D 



Fig. 353. Seeds of Aster, Whiteweed and Horseweed. A, Aster salicifoUus. B, 

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

 canadensis). D, Whiteweed (Brigeron romosus). 



(A and B, drawings by Charlotte M. King; C and D, after HlUman; 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. tradesccmti 

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

 mcmdU. The duplex hairs of Aster laevis, A. dblongif alius, A. navae- 

 wngliae and A. mvltiflorus are slender. 



Fig-. 354A Fig. 354B Fig. 8540 Pig. 354D Fig. 354E 



Fig. 354. Aohenial hairs of Asters. A. Aster novae-angliae. B. Aster 

 salicifoUus. C. Aster tradescanti. D. Aster oVlongifolms. E. Aster 

 multiflorus. 



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

 31 



