37* 



COMPOSITAE. 



VOL. III. 



19. SIDERANTHUS Fraser, Cat. 1813; Sweet, Hort. Brit. 227. 1826. 

 [ERIOCARPUM Nutt. Trans. Am. Phil. Soc. (II) 7: 320. 1841.] 



Perennial or annual herbs or shrubs with alternate spinulose-dentate or lobed leaves and 

 many-flowered heads of tubular or of both tubular and radiate yellow flowers (heads rarely 

 without rays). Involucre hemispheric to campanulate, its bracts imbricated in several series, 

 the outer ones gradually smaller. Receptacle flat or convex, generally foveolate, naked. 

 Ray-flowers fertile. Disk-flowers usually perfect. Anthers obtuse and entire at the base. 

 Style-branches flattened, their appendages short, lanceolate. Achenes oblong or obovoid, 

 obtuse, white-tomentose, or canescent, usually 8-io-nerved. Pappus of 1-3 series of numer- 

 ous capillary persistent more or less unequal bristles. [Greek, iron-flower.] 



About 15 species, natives of America. Besides the following, about 10 others occur in the 

 western, parts of the United States. Type species: Sideranthus spinulosus (Nutt.) Sweet. 



Rays none ; leaves dentate. 

 Rays present. 



Leaves dentate ; annual. 



Leaves pinnatifid ; perennial. 



1 . S. grindelioides. 



2. S. annuus. 



3. S. spinulosus. 



i. Sideranthus grindelioides (Nutt.) Britton. 

 Rayless Sideranthus. Fig. 4208. 



Eriocarpum grindelioides Nutt. Trans. Am. Phil. Soc. 

 (II.) 7: 321. 1841. 



Aplopappus Nuttallii T. & G. Fl. N. A. 2 : 240. 1842. 

 Sideranthus grindelioides Britton, Manual 932. 1901. 



Perennial by a deep woody root, finely pubescent; 

 stems tufted, simple, erect, 4'-i2' high. Leaves ob- 

 long-lanceolate to spatulate, sessile, or the lower peti- 

 oled, i'-i' long, firm, acute or obtusish, spinulose- 

 dentate ; heads several or solitary, terminating the 

 stem or branches; peduncles i' long, or less; invo- 

 lucre campanulate, its bracts linear, acute, puberulent, 

 their tips somewhat spreading, the outer shorter than 

 the inner ; achenes densely silky tomentose. 



In dry soil, South Dakota to Assiniboia, Nebraska, 

 New Mexico and Arizona. July-Aug. 



2. Sideranthus annuus Rydb. Viscid 

 Sideranthus. Fig. 4209. 



Sideranthus annuus Rydb. Bull. Torr. Club 31 : 



653. 1904. 

 Aplopappus rubiginosus A. Gray, Syn. Fl. i 2 : 130. 



1884. Not T. & G. 



Viscid, glandular-pubescent, erect, annual, 

 branched near the summit, i-3 high. Leaves 

 sessile, or the lowest narrowed into short 

 petioles, oblong, lanceolate, or oblanceolate, 

 conspicuously dentate with distant awn-point- 

 ed teeth, acute or obtusish at the apex. \\'-2.\' 

 long, 2"-6" wide ; heads several, cymose- 

 paniculate, 8"-i5" broad; involucre hemi- 

 spheric, its bracts linear-subulate with spread- 

 ing tips ; rays large ; pappus bristles rigid, very 

 unequal ; achenes villous-canescent, turbinate, 

 not compressed. 



On plains and in canons, Nebraska, Kansas 

 and Colorado. Erroneously referred in our first 

 edition to Eriocarpum rubiginosum. Aug.-Sept. 



