COMPOSITAE. 253 



Gnaphalium microcephalum Nutt. Pubescence woolly, dense, white, close; 

 stems several, slender, erect, 30-60 cm. high; leaves linear or the lower lanceo- 

 late, decurrent at base; heads in clusters of several, these paniculate; involucres 

 turbinate to'campanulate, woolly only at base, 3-4 mm. high; bracts bright 

 white, scarious, obtuse. In gravelly or sandy soil. 



Gnaphalium chilense Spreng. Erect, very leafy, 30-60 cm. high, simple 

 or branched below; persistently tomentose, not glandular; leaves linear- 

 lanceolate or somewhat spatulate, acute, S-8 cm. long, scarcely decurrent at 

 base; heads 4-S mm. high, in one or few dense clusters; involucre hemispheric, 

 the bracts greenish-white, oblong, obtuse; akenes glandular. Prairies and 

 open woods. 



377. IVA. 



Herbs; leaves simple, at least some of the lower opposite; 

 heads small, nodding, in the axils of the leaves or in terminal 

 spikes or panicles; flowers monoecious, in the same head; a few 

 marginal ones pistillate, the others staminate and more numerous ; 

 bracts of the involucre few, rounded, commonly united into a cup; 

 receptacle chaffy, with scales subtending the sterile flowers; 

 akenes obovate, thick. 



Iva xanthiifolia Nutt. Annual, tall and stout, 1-2 m. high, pubescent or 

 puberulent; leaves opposite or the uppermost alternate, broadly ovate, 

 acuminate, incisely serrate, scabrous above, 3-ribbed, 6-12 cm. long; petiole 

 stout, with a few scattered stout hairs; panicles terminal and in the axils of 

 the upper leaves, bractless, large and dense; heads sessile or nearly so, about 

 2 mm. broad, hemispherical; involucral bracts in two series of 5 each, the outer 

 broadly ovate, the inner obovate or oblong and truncate; akenes usually 5. 

 Introduced along railways, and becoming weedy. 



Iva axillaris Pursh. See page 280. 



378. ADENOCAULON. 



Slender perennial herbs, with alternate petioled leaves, green 

 above, white-woolly beneath; heads few, small, 5-10-flowered, 

 glandular, in a loose panicle; involucral bracts in one row; re- 

 ceptacle flat, naked; flowers all tubular, the marginal pistillate, 

 fertile, the central perfect but sterile; akenes elongated at 

 maturity, club-shaped; pappus none. 



Adenocaulon bicolor Hook. Stem 30-90 cm. high; leaves triangular, 

 somewhat cordate, with angular toothed margins; petioles margined. In 

 dense woods in the mountains. 



379. ARTEMISIA. Sagebrush. Wormwood. 



Herbs or undershrubs, bitter and odorous; leaves alternate, 

 usually dissected; heads numerous, small, in racemes or panicles, 

 several to many-flowered, discoid; flowers yellow or yellowish, 

 all tubular, the outermost series pistillate or all alike, the more 

 numerous perfect flowers either fertile or sterile; involucral -scales 

 dry, imbricated in a few rows, appressed; receptacle flattish to 

 hemispherical, naked, sometimes hairy; pappus none; corollas of 



