356 COMPOSITAE HYMENOPAPPUS 



RIGIOPAPPUS 



Achenes narrow, quadrangular. Pappus of several Scarious scales 

 with callous-thickened opaque base, rarely wanting. 



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

 stems densely cinereous, much branched, 4-13 inches high, very leafy; 

 leaves opposite, or the uppermost alternate, 6-18 lines long, palmately 3-5- 

 parted into linear obtuse or obtusish, entire segments, finely cinereous on 

 both sides ; heads short-peduncled : involucre campanulate, or becoming 

 hemispheric, 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, 37. "Cihereous-puberulent 

 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 paleae 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 spread- 

 ing lobes. Style-branches with short and thick conical appendages 

 Achenes obpyramjdal, 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. filifolius Hook. Fl. i, 317. Perennial from a deep woody root: 

 stems usually tufted, 10-34 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 nar- 

 rowly 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 : paleae 

 of the pappus short. Brit. Columbia to California, New Mexico and Ne- 

 braska, 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- 

 ligule, not surpassing the disk. Disk-flowers more numerous, 



