93 2 FLORA. 



18. PRIONOPSIS Nutt. 



A glabrous annual or biennial herb, leafy to the top. with sessile spinulose- 

 dentate leaves, and large heads of yellow radiate and tubular flowers. Involucre 

 broadly hemispheric, its bracts imbricated in several series, lanceolate, acuminate, 

 the outer more or less spreading. Receptacle naked. Disk-flowers perfect, their 

 corollas 5 -toothed. Ray- flowers very numerous, pistillate. Achenes glabrous, 

 those of the ray-flowers broader than those of the disk; pappus of a few deciduous 

 rigid unequal bristles, the outer very short. [Greek, resembling a saw, referring 

 to the leaf-margins.] A monotypic genus. 



I. Prionopsis ciliata Nutt. PRIONOPSIS. (I. F. f. 3665.) Stem erect, stout, 

 branched, very leafy, 6-15 dm. high. Leaves sessile, oval or the lower obovate, 

 obtuse, conspicuously veined. 2-7 cm. long, 1-3 mm. wide, sharply serrate with 

 bristle-pointed teeth; heads few, clustered, stalked or nearly sessile, 25-35 mm. 

 broad; involucre depressed-hemispheric, its bracts glabrous; achenes of the ray- 

 flowers ellipsoid, those of the disk-flowers oblong, the central sterile; pappus-bristles 

 rigid, the inner ones rough or ciliate. On hillsides and river- banks, Mo. and Kans. 

 to Tex. Aug.-Sept. 



19. SIDER&NTHUS Fraser. 



LERIOCARPUM Nutt.] 



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, gen- 

 erally foveolate, naked. Ray-flowers fertile. Disk-flowers usually perfect. An- 

 thers obtuse and entire at the base. Style-branches flattened, their appendages 

 short, lanceolate. Achenes oblong or obovoid, obtuse, white-tomentose. or canes- 

 cent, usually 8-io-nerved, Pappus of 1-3 series of numerous capillary persistent 

 more or less unequal bristles. [Greek, iron-flower.] About 15 species, of America. 

 Besides the following, about 1 1 others occur in the western U. S. 



Rays none; leaves dentate. i. S. grindclioides ; 

 Rays present. 



Leaves dentate; annual. 2. S. rubiginosus. 

 Leaves pinnatifid; perennial. 



Tomentose-canescent. 3. S. spinulosus. 



Glabrous or slightly puberulent. 4. S. glaberrimus. 



1. Sideranthus grindelioides (Nutt. ) Britton. RAYLESS SIDERANTHUS. (I. F. 

 f. 3666.) Perennial by a deep woody root, finely pubescent; stems tufted, simple, 

 erect, 1-3 dm. high. Leaves oblong-lanceolate to spatulate, sessile, or the lower 

 petioled, 1-2.5 cm. long, firm, spinulose-dentate; heads terminating the stem or 

 branches; involucre campanulate, its bracts linear, acute, puberulent, their tips 

 somewhat spreading, the outer shorter than the inner; achenes densely silky tomen- 

 tose. In dry soil, N. W. Terr, to S. Dak., Neb., Utah and Ariz. July-Aug. 

 \_Eriocarpiim grindelioides Nutt. ] 



2. Sideranthus rubiginosus (T. & G.) Britton. VISCID SIDERANTHUS. (I. 

 F. f. 3667.) Viscid, glandular-pubescent, erect, annual, branched near the sum- 

 mit, 3-9 dm. high. Leaves sessile, or the lowest narrowed into short petioles, 

 oblong, lanceolate, or oblanceolate. conspicuously dentate with distant awn-pointed 

 teeth, 3-6 cm. long. 4-12 mm. wide; heads several, cymose paniculate, 16-30 mm. 

 broad; involucre hemispheric, its bracts linear-subulate with spreading tips; pap- 

 pus-bristles rigid, very unequal; achenes villous-canescent, turbinate, not com- 

 pressed. Neb. and Colo, to Tex. Autumn. 



3. Sideranthus spinulosus (Nutt.) Sweet. CUT-LEAVED SIDERANTHUS. 

 (L F. f. 3668.) Canescent, much branched at the base, perennial from thick 

 woody roots, 1-4 dm. high. Leaves pinnatifid, sessile, linear to ovate in out- 

 line, 1-3.5 cm - l n g> 2 ~S mm - wide, the lobes with bristle-pointed teeth; heads 

 several or numerous (rarely solitary), 12-25 mm - broad; involucre hemispheric, its 

 bracts linear, acute, appressed; achenes pubescent, narrowed below; pappus soft 

 and capillary. In dry soil, N. W. Terr, to Neb. and Tex., Mont., Ariz, and Mex. 

 March-Sept. 



