THISTLE FAMILY 943 



2. H. tomentosus Rydb. Biennial; stem 3-4 dm. high, leafy and branched 

 above; leaves 5-7 cm. long, bipinnately divided into linear segments, 4-10 mm. 

 long; involucre densely woolly, somewhat turbinate, 8 mm. high and broad; 

 flowers yellow; corolla throat a little over 1 mm. long, broadly campanulate, of 

 about the same length as the lobes. Dry plains: s Utah. Son. 



3. H. scaposus Rydb. Perennial; stem ahnost naked, with 1-2 reduced 

 leaves, more or less densely tomentose; leaves mostly basal, 5-7 cm. long, bi- 

 pinnately divided into linear segments, 3-10 mm. long, densely tomentose, 

 especially at the base; heads about 1 cm. high and broad; bracts obovate, with 

 yellowish or purplish scarious margins; corollas yellow; throat nearly 2 mm. long, 

 campanulate and longer than the lobes; squamellae of the pappus fully 2 mm. 

 long, longer than the tube of the corolla. Dry hills: N.M. — Utah — Nev. — Ariz. 

 Son. My-Jl. 



4. H. arenosus Heller. A white-tomentose perennial, with branched woody 

 caudex; stems several, 2-4 dm. high, densely tomentose, especially at the base, 

 2-4-leaved; leaves mostly basal, twice pinnately divided into linear-filiform 

 divisions 3-15 mm. long, 1 mm. wide; heads about 8 mm. high, 8-10 mm. broad; 

 bracts oblong, with narrow scarious margins, tomentose; corollas yellow; throat 

 nearly 2 mm. long; achenes long-silky; pappus rather short, about 1 mm. long, 

 but not hidden by the hairs. On dry hills: N.M. — Colo. — Ariz. Son. — Sub- 

 monl. My-Jl. 



5. H. cinereus Rydb. Perennial, with a cespitose caudex; stems about 2 

 dm. high, branched; leaves bipinnately divided into linear segments 1-2 cm. 

 long and about 1 mm. wide, sparingly grayish tomentulose; heads 8-10 mm. 

 high, 10-12 mm. broad; bracts oblong-obovate, with narrow scarious margins; 

 corollas yellow; throat about 1.5 mm. long, broadly campanulate, longer than 

 the lobes; achenes loosely villous. H. ochroleucus Greene. Dry hills and plains: 

 Colo. — Utah. Siibmont. — Suhalp. My-Jl. 



6. H. filifolius Hook. Perennial; stem 2-3.5 dm. high, sparingly branched; 

 leaves similar to those of H. tenuif alius; heads few, 1&-15 mm. broad; bracts 

 obovate-oblong, with broad scarious margins, tomentose; corollas bright yellow; 

 throat about 1.5 mm. long; achenes densely villous, the long hairs hiding the 

 small pap])us; squamellae less than 1 mm. long. On plains and prairies: Alta. — 

 Sask. — Kans. — N.M. — ^Nev. — Wash. Plain — Subniont. Je-S. 



7. H. luteus Nutt. Perennial; stem 1-2 dm. high, with a few reduced 

 leaves and few heads; basal leaves 2-7 cm. long, twice pinnately divided into 

 short lobes 1-5 mm. long; heads about 1 cm. high, 10-15 mm. broad; bracts 

 oblong, broadly scarious-margined ; corolla yellow; throat about 1 mm. long; 

 achenes densely villous-hirsute ; scales of the pappus short, about 0.5 mm. long. 

 Bad-lands and clay-hills: Wyo. Submont. — Mont. My-Jl. 



8. H. parvulus Greene. Perennial; stem 1-2 dm. high, scapiform, slightly 

 tomentose; basal leaves 5-8 cm. long, bipinnatifid, with narrowly linear-filiform 

 divisions, 5-12 mm. long, grayish-tomentose; stem-leaves few and small; invo- 

 lucres turbinate, 6-7 mm. high and broad; bracts oblong-obovate, greenish yellow, 

 sparingly tomentulose; corollas brownish yellow; throat cylindro-campanulate, 

 1.5-2 mm. long, about 3 times as long as the teeth; achenes short villous. Dry 

 hills: Colo. Submont. Jl-Au. 



9. H. lugens Greene. Perennial; stem scapiform, 2-3 dm. high, white- 

 tomentulosc; leaves bipinnatifid with fiUform divisions, permanently white- 

 tomentose, 5-10 cm. long; stem-leaves small and few; involucres nearly 1 cm. 

 high, 12-15 mm. broad; bracts elliptic, the outer usually with purple-tinged 

 margins; corolla-throat cylindraceous, 3-4 mm. long, 3-4 times as long as the 

 lobes; pappus-scales oblong-obovate, as long as the corolla- tube. Dry ridges: 

 s Calif. — Utah — Ariz. Son. — Submont. My-Au. 



10. H. eriopodus A. Nels. Perennial; stem 3-10 cm. high, leafy; leaves 

 numerous, bipinnately divided into filiform divisions, sparingly tomentulose or 

 glabrate; involucres about 1 cm. high and 12-15 mm. broad; bracts elliptic, 

 scarious-margined, sometimes purplish; corolla-throat about 3 mm. long, cyUndro- 



