Genus 50.] 



THISTLE FAMILY. 



353 



4. Boltonia decurrens (T. & G.) 



Wood. Clasping-leaved Boltonia. 



(Fig. 3731 •) 



BoUonia glaslifolia var. (?) decurrens T. & G. Fl. 



N. .v. 2: 1S8. 1841. 

 Boltonia decurrens Wood, Bot. & Flor. 166. 1870. 

 Bollonia asleroides var. decurrens Engelm. ; A Gray, 



Syii. Fl. i: Part 2, 166. 1884. 



Stout, 3^-6° high, branched above. Leaves ob- 

 long-lanceolate or elongated lanceolate, mucron- 

 ate at the apex, those of the stem decurrent and 

 sagittate at the base, 3'-6' long, 6"-8" wide, 

 those of the branches smaller and merely sessile 

 or some of them also decurrent; heads 2%"-^," 

 high; involucre hemispheric; rays about 3" long, 

 violet or purple; pappus of several or numerous 

 short scales and 2 very slender bristles. 



In wet prairies, Illinois and Missouri. Aug.-Sept. 



30. SERICOCARPUS Nees, Gen. & Sp. Ast. 148. 1833. 



Erect perennial herbs, with alternate leaves, aud middle-sized heads of both tubular and 

 radiate flowers, in terminal cymose panicles. Involucre ovoid, oblong, or campanulate, its 

 bracts coriaceous, with herbaceous or squarrose tips, imbricated in several series, the outer 

 shorter. Receptacle small, foveolate. Ray-flowers white, pistillate. Disk-flowers mostly 

 perfect, their corollas tubular, narrow, yellowish or purplish, 5-lobed. Anthers obtuse and 

 entire at the base. Style-branches with lanceolate-subulate appendages. Achenes slightly 

 compressed, linear-oblong, i-uerved on each side, pubescent. Pappus of numerous capillary 

 scabrous bristles, the outer usually shorter. [Greek, silky fruit, referring to the achenes.] 



Four known species, natives of North America. Besides the following, another occurs on the 

 northwestern coast of North America. 

 Leaves entire, linear, spatulate, or obovate, rigid. 



Glabrous, or nearly so; leaves linear or Hnear-spatulate. i. 5. linifolius. 



Puberulent or scabrous; leaves obovate. 2. S. bifoliatus. 



Leaves dentate, oblong, or obovate, thin. 3. .?. asleroides. 



I. Sericocarpus linifolius (I^.) B.S.P. Narrow-leaved White-topped Aster. 



(Fig. 3732.) 



^Ai^^^m^ A _ „ ,-,i^ll>A3iK:^«Ste5,=.=n Conyza linifolia L. Sp. PI. 861. 1753. 



Sericocarpus solidagineus Nees, Gen. & Sp. 

 Ast. 149. 1832. 



Sericocarpus linifolius B.S.P. Prel. Cat. N. Y. 

 25. 1888. 



Glabrous or very nearly so throughout; 

 stem rather slender, striate, i°-2!^° high. 

 Leaves linear or linear-spatulate, spreading, 

 faintly 3-nerved, thick, entire, obtuse at the 

 apex, narrowed at the base, i''-2'long, l>^"- 

 3" wide, sessile, or the lowest on short mar- 

 gined petioles, their margins scabrous; heads 

 about 3"-4" high, clustered in 2's-6's at the 

 ends of the cymose branches; involucre ob- 

 long-campanulate, its bracts oblong, obtuse, 

 the outer with somewhat spreading or 

 reflexed green tips, the inner scarious and 

 often lacerate or ciliate at the apex; rays 4 

 or 5, about 4"-5" long; pappus white. 



In dry, usually sandy soil, Canada (according 

 to Gray), Vermont to Ohio, Georgia and Louisi- 

 ana. June-Sept. 



23 



