Genus 29. 



THISTLE FAMILY 



4. Boltonia decurrens ( T. & G.) Wood. 

 Clasping-leaved Boltonia. Fig. 4278. 



Bolonia glaslifolia var. (?) decurrens T. & G. Fl. N. 

 A. 2 : 188. 1 841. 



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



Boltonia asteroides var. decurrens Engelm. ; A. Gray, 

 Syn. FI. 1: Part 2, 166. 1884. 



Stout, 3-6 high, branched above. Leaves oblong- 

 la nceolate or elongated-lanceolate, mucronate 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* "-3" high ; involucre hemi- 

 spheric ; rays about 3" long, violet or purple ; pap- 

 pus of several or numerous short scales and 2 very 

 slender bristles. 



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

 Perhaps a race of B. asteroides. 



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

 Erect perennial herbs, with alternate leaves, and 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-nerved 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. Type species: Sericocarpus solidagineus (Michx.) Nees. 

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



Glabrous, or nearly so ; leaves linear or linear-spatulate. 1. 5. Hnifolius. 



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



Leaves dentate, oblong, or obovate, thin. 3. i". asteroides. 



i. Sericocarpus linifolius (L.) B.S.P. Narrow-leaved White-topped Aster. 



Fig. 4279. 



Conysa linifolia L. Sp. PI. 861. 1753. 



Aster solidagineus Michx. Fl. Bor. Am. 2: 108. 



1803. 

 Sericocarpus solidagineus Nees, Gen. & Sp. Asf. 



149. 1832. 

 Sericocarpus linifolius B.S.P. Prel. Cat. N. Y. 26. 



1888. 



Glabrous or very nearly so throughout ; stem 

 rather slender, striate, l-2i high. Leaves 

 linear or linear-spatulate, spreading, faintly 

 3-nerved, thick, entire, obtuse at the apex, nar- 

 rowed at the base, l'-2' long, il"-3" wide, ses- 

 sile, or the lowest on short margined petioles, 

 their margins scabrous; heads about 3"-4" 

 high, clustered in 2's-6's at the ends of the 

 cymose branches ; involucre oblong-campanu- 

 late, 2"-3l" long, its bracts oblong, obtuse, the 

 outer with somewhat spreading or reflexed 

 green tips, the inner scarious and often lacer- 

 ate or ciliate at the apex; rays 4 or 5, about 

 5" long; pappus white. 



In dry, usually sandy soil, Maine to Ohio, Geor- 

 gia and Louisiana. Erroneously recorded from 

 Canada. June-Sept. 



