1024 CICHORIACEAE 



1 or 2 small calyculate ones. Achenes gradually tapering downward from the 

 truncate summit, 4-5-ridged. Pappus of white soft capillary bristles. 



1. P. exigua (A. Gray) Rydb. Stem 1-2 dm. high, divaricately branched; 

 basal leaves spatulate or oblong in outline, 2-3 cm. long; involucres 3-4 mm. 

 high; calyculate bracts small, ovate; bracts proper 4-5, oblong. Lygodesmia 

 exigua A. Gray. Stony hills: Tex. — Colo. — Utah — se Calif. Ap-Je. 



19. NABALUS Cass. Rattlesnake-root. 



Perennial caulescent herbs. Heads small, clustered, and usually nodding. 

 Involucre narrow, cylindric to campanulate; bracts narrow, in 1 or 2 subequal 

 series, subtended by a few small calyculate ones. Receptacle flat, naked. Plow- 

 ers pale, cream-colored or purplish. Achenes oblong or coliminar, terete or 

 5-angled, often 10-ribbed, sometimes slightly tapering towards the base. Pap- 

 pus of numerous capillary, rather rigid, pale or bro'mi bristles. [Prenanthes 

 Vaill.] 



Basal leaves oblanceolate or spatulate; inflorescence liirsute. 1. N. racemosus. 



Basal leaves cordate, sagittate, or hastate; inflorescence glabrous or puberulent. 



Leaves variously lobed or cleft ; heads noddmg ; calyculate bracts ovate, very short. 



2. N. albus. 

 Leaves dentate; flowering heads not nodding; calyculate bracts linear, half as long as 

 the bracts proper. 3. N. sagittatus. 



1. N. racemosus (Mich.x.) DC. Stem 5-10 dm. high, glabrous or pubes- 

 cent above; basal leaves glabrous, entire or dentate, with winged petioles; stem- 

 leaves sessile, oblong or elliptic, partly clasping; heads in a long spike-like thyrsus; 

 involucres campanulate, 12-14-flowered, 10-12 mm. high; bracts narrowly linear, 

 obtuse, hirsute; flowers rose or purplish; pappus fulvous. Moist groimd: N.B. — 

 N.J. — Colo. — Mont. — Alta. Plain — Mont. Au-S. 



2. N. albus (L.) Hook. Stem 5-15 dm. high, glabrous, often tinged with 

 purple; leaves petioled; blades deltoid-hastate, denticulate, dentate, lobed, or 

 divided, or the upper lanceolate and entire, thin, glabrous, paler beneath; heads 

 nimierous, paniculate, pendulous, about 12 mm. high and 6 mm. broad; prin- 

 cipal bracts about 8, purplish, linear; corollas greenish or white; pappus reddish 

 brown. Open woods: Me. — Ga. — Ky. — Minn. — Sask. Boreal. Au-S. 



3. N. sagittatus (A. Gray) Rydb. Stem glabrous, 3-7 dm. high; lower 

 leaves petioled; blades sagittate, hastate or ovate, dentate or lobed, with la-nceo- 

 late saUent lobes, glabrous, thin; upper leaves sessile, lanceolate, acuminate; 

 heads in a narrow panicle, at first erect, in fruit spreading or rarely somewhat 

 deflexed; involucres about 12 mm. high; bracts linear, green; flowers tinged with 

 purple; pappus sordid. Along rivers: Mont. — Ida. Submonl. Jl-S. 



20. CREPIS L. 



Annual, bieimial, or perennial (all ours), mostly caulescent herbs. Involucre 

 cylindric or campanulate; bracts in a single series, equal, with a more or less 

 thickened midrib ; a small outer calyculum present or absent. Flowers yellow. 

 Achenes 10-30-ribbed, narrowed towards the summit. Pappus of numerous, 

 white and soft bristles. 



Plant neither canesccnt nor furfurasccnt ; lieads hemispherical to turbinate. 



Involucres glabrous or toiucni ulosc when young; neitlier liirsute nor glandular. 



Involucres and pcdiinclis imiu lUulosc, at least when young. 1. C. tomentulosa. 

 Involucres glaltrous or slightly i)uberulent when young. 2. C. glaitca. 



Involucres and pcduiicles liirsute or glandular or both. 

 Plant 3-10 dm. high; heads few or many. 



Leaf-hlades oblanceolate or oblong to linoar-oblanccolatc. 



Leaves long-petioled ; petioles half as long to fully as long as the blades, 

 not winged. 

 Blades of the basal leaves broadly oblanceolate; stem usually with 1-2 



leaves; involucres over 1 cm. high. 3. C. pctiolala. 



Blades of the basal leaves narrowly linear-lanceolate or Unear-oblanceo- 

 late; stem scapiform; involucres less than 1 era. high. 



4. C. glaucella. 

 Leaves subsessile or with short winged petioles. 



Leaves glabrous or nearly so; involucres mth a few short hairs. 



5. C. perplexans. 



