356 COMPOSITE hymenopappus 



RIGIOPAPPUS 



Achenes narrow, quadrangular. Pappus of several scarious scales 

 with callous-thickened opaque base, rarely wanting. 



B. oppositifolia Nutt. T. & G. Fl ii, 376. Herbaceous perennial ; stems 

 densely cinereous, much branched, 4-12 inches high, very leafy : leaves 

 opposite, or the uppermost alternate, 6-18 lines long, palmately 2-5-parted 

 into linear obtuse or obtusisb, entire segments, finely cinereous on both 

 sides : heads short-peduncled : involucre campanulate, or becoming hemi- 

 spheric, its bracts oblong, obtuse, densely tomentose : rays 5-7, short : 

 achenes linear-oblong, glandular-pubescent: pappus of 4-8 spatulate to 

 lanceolate paleae with thickened bases. Dry plains, eastern Oregon to 

 Nebraska and New Mexico. 



B. nudicaulis Gray Proc. Am. Acad, xix, 27. " Cinereous-puherulent 

 and glabrate, upper part of the scapiform stem and involucre minutely 

 glandular, a span or two high : leaves nearly all radical, oval or spatulate"- 

 oblong, (an inch or more long), tapering into a slender petiole : heads soli- 

 tary, or few and somewhat corymbosely paniculate, nearly half-inch high : 

 involucre hemispherical, of about 10 oblong bracts : rays 6-9, oblong: pap- 

 pus fully half the length of the cuneate linear sparsely hairy achene ; the 

 thin margins of the palese of the pappus erose and the short-excurrent awn 

 barbellate-hispidulous. Wind River Mountains N. W. Wyoming. ,, To 

 be looked for in Idaho. 



63 HYMENOPAPPUS L'Her. Michx. Fl. ii, 103. 



Perennial or biennial herbs with sulcate-angled erect stems, 

 alternate mostly once or twice pinnatifid or parted leaves, and 

 corymbosely cymose or solitary pedunculate heads of yellow or 

 white flowers. Involucre campanulate, many-flowered, of 6-12 

 mostly appressed bracts with scarious-membranaceous usually 

 colored tips. Rays none. Disk-corollas numerous, all alike, 

 with narrow tube, abruptly dilated throat and reflexed or widely 

 spreading lobes. Style-branches with short and thick conical 

 appendages Achenes obpyramidal, 4-5-angled, with attenuate 

 base, the faces 1-3-nerved. Pappus of 10-20 thin-scarious and 

 mostly hyaline obtuse scales; sometimes very short or obsolete. 



H. fllifolius Hook. Fl. i, 317. Perennial from a deep woody root : stems 

 usually tufted, 10-24 inches high, woolly when young, densely leafy toward 

 the base, usually naked and sparingly branched above ; leaves rather rigid 

 once or twice or the radical thrice pinnatifid into very narrowly linear or 

 filiform divisions their margins soon revolute: heads few or solitary, 4-6 

 lines high; bracts of the involucre oblong, usually densely woolly, with 

 whitish or purplish tips: corollas white to yellow, its reflexed lobes very 

 much shorter than the throat : achenes densely villous : palese of the pappus 

 short. Brit. Columbia to California New Mexico and Nebraska, east- -of 

 the Cascade Mountains. 



64 RIGIOPAPPUS Gray Proc. Am. Acad, vi, 548. 



Small slender annual with opposite leaves and small heads of 

 yellow flowers terminating the branches. Heads inconspicuously 

 radiate. Involucre turbinate-campanulate, of numerous narrowly 

 linear rather rigid herbaceous bracts which are somewhat invo- 

 lute at maturity ; many-flowered, Receptacle flat. Ray-flowers 

 5-15, the corolla with slender tube and oblong entire or 2-tooth- 



