THISTLE FAMILY 931 



Leaves usually all opposite, distinctly triple-nerved. 



Leaves lanceolate, thick, often toothed, yellowish green, the 



lower distinctly petioled. 11. H. subtuberosus. 



Leaves linear-lanceolate, dark green, entire, all subsessile. 



12. H. Cusickii. 

 Stem, except the upper portion, glabroiLs and glaucous; leaves mostly 



all petioled. 

 Lower leaves coarsely toothed; bracts hirsute ciUate. 



13. H. grosse-serratus. 

 All leaves distantly and minutely denticulate or subentire; bracts 



not ciUate or ciUate merely at the base. 

 Leaves lanceolate, often somewhat triple-ribbed. 



Leaves aU opposite; bracts ciUate on the margins. 



11. //. subtuberosus. 

 Leaves mostly alternate; bracts cihate only below the middle. 



14. //. fascicularis. 

 Leaves narrowly lineai -lanceolate, not triple-ribbed. 



15. H.NuUalUL 



1. H. lenticularis Dougl. Stem 1-2 m. high; leaves mostly alternate, the 

 lower long-i)etioled; blades ovate, 1-2 dm. long, sometimes cordate at the base, 

 dentate, hispidulous-scabrous, the upper more lanceolate, subentire; involucres 

 1.5-2 cm. high, 4-5 cm. broad; achenes grayish strigose, about 6 mm. long. 

 Closely related to the cultivated H. annuus, which has larger, more nodding 

 heads, looser bracts, more salient teeth to the leaves and larger achenes, often 

 1 cm. long. Plains and alluvial soil, also in waste places and cultivated ground: 

 Sask. — Tex. — Calif. — Wash. Plain — Submont. Je-S. 



2. H. aridus Rydb. Stem 3-8 dm. high, more or less hispid; leaves all 

 petioled; blades lanceolate, 4-7 cm. long, entire or crenate, acute, hispid-scabrous 

 on both sides; disk 1.5-2 cm. wide; ligules oblong to oval, 15-20 mm. long, 6-8 

 mm. wide; achenes cuneate, almost black, finely strigose, about 5 mm. long. 

 Arid soil: Sask. — Neb. — N.M. — Ariz. — B.C. Plain — Submont. Je-S. 



3. H. petiolaris Nutt. Stem 3-10 dm. high, hirsute-strigose ; leaves peti- 

 oled; blades lanceolate or ovate-lanceolate, mostly cuneate at the base, 5-8 cm. 

 long, hispidulous-scabrous; involucres about 1 cm. high, 2-3 cm. broad; Ugules 

 golden yellow, 1.5-2 cm. long; achenes about 5 mm. long, strigose. Dry plains 

 and waste places: Sask. — Mo. — Tex.^ — Calif.^ — B.C. Plain — Mont. Je-S. 



4. H. orgyalis DC. Stem smooth and glabrous, 5-30 dm. high, very leafy; 

 leaves mostly alternate, narrowly Hnear, 2-4 dm. long, 4-8 mm. wide, scabrous- 

 puberulent; involucres fully 1 cm. high and about 2 cm. wide; bracts hnear- 

 subulate, long-attenuate, ciUolate on the margins; rays 15-18 mm. long. Dry 

 plains: Mo. — Tex. — e Colo. Plain. Au-S. 



5. H. subrhomboideus Rydb. Perennial, with a rootstock; stem 3-6 dm. 

 high, terete, tinged with red, sparingly hirsute; leaves opposite; blades firm, very 

 scabrous, triple-veined, serrate, the lower ovate or obovate-spatulate, the upper 

 rhombic-ovate or rhombic-lanceolate, 5-10 cm. long; heads sohtary, rarely 2 or 

 3; involucres 10-12 mm. high and 1.5-2 cm. broad; bracts in 4 or 5 series, oblong, 

 acutish, white-cQiolate; ligules about 1.5 cm. long. Plains: Man. — Ai-k. — N.M. 

 — Alta. Plain — Submont. Jl-S. 



6. H. pumilus Nutt. Perennial, with a woody crown; stem 3-6 dm. high, 

 hispid ; leaves opposite, short-petioled ; blades ovate or lanceolate, entire or nearly 

 so, acute or obtuse, 3-10 cm. long, very scabrous, hispid on the veins, 3-ribbed; 

 involucres nearly 1 cm. high and about 2 cm. broad; Ugules 15-20 mm . long. 

 Plains and mountains: Wyo. — Colo. Plain — Submont. Je-Au. 



7. H. tuberosus L. Perennial, with tubers; stem 1-3 m. high, branching 

 at the summit, more or less hirsute; lower leaves usually opposite, the upper 

 alternate, petioled; blades ovate or subcordate, acuminate, firm, 3-ribbed, sca- 

 brous above, pubescent beneath, 5-30 cm. long, usually dentate; involucres 

 about 1.5 cm. high, 2-3 cm. broad; bracts lanceolate, attenuate, hirsute at least 

 on the margins; hgules 12-20, 2.5-3.5 cm. long. Alluvial soil: N.S. — Ga. — .\rk. — 

 Neb. — Sask. Plain. Au-0. 



8. H, divaricatus L. Perennial, with a rootstock; stem 3-10 dm. high, 

 simple, smooth below, hispidulous-scabrous above; leaves opposite, subsessile, 



