Genus 30.] 



THISTLE FAMILY. 



353 



4. Boltonia decurrens (T. & G.) 



Wood. Clasping-leaved Boltonia. 



(Fig. 3731.) 



Boltonia Q-lasiifolia var. (?) decurrens T. & G. Fl. 

 N. A. 2: 188. 1841. 



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

 Boltonia asteroides var. decurrens Engelm. ; A Gray, 

 Syn. Fl. 1: Part 2, 166. 1S84. 



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 // -S // wide, 

 those of the branches smaller and merely sessile 

 or some of them also decurrent; heads 2> // -3 // 

 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. 



'33- 



30. SERICOCARPUS Nees, Gen. & Sp. Ast. 148. 18: 



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. 



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



Glabrous, or nearly so; leaves linear or linear-spatulate. 



Puberulent or scabrous; leaves obovate. 

 Leaves dentate, oblong, or obovate, thin. 



1. S. linifolius. 



2. S. bifoliatus. 



3. S. asteroides. 



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



(Fig. 3732.) 



Conyza linifolia L. Sp. PI. 861. 1753. 



Sericocarpus solidagineus Nees, Gen. & Sp. 

 Ast. 149. 1832. 



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



26. 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, 1%"- 

 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 



