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. 

 btem, except the upper portion, glabrous arid glaucous; leaves mostly 



all petioled. 

 Lower leaves coarsely toothed; bracts hirsute cilia te. 



13. H. grosse-serratus. 

 All leaves distantly and minutely denticulate or subentire; bracts 



not ciliate or ciliate merely at the base. 

 Leaves lanceolate, often somewhat triple-ribbed. 

 Leaves all opposite; bracts ciliate on the margins. 



11. H. subtuberosus. 

 Leaves mostly alternate; bracts ciliate only below the middle. 



14. H. fascicularis. 

 Leaves narrowly linear -lanceolate, not triple-ribbed. 



15. H.Nuttallii. 



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

 lower long-petioled; 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, 4r-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 SubmonL Je-S. 



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

 petioled; blades lanceolate, 4r~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 SubmonL 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; ligules 

 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 linear, 2-4 dm. long, 4-8 mm. wide, scabrous- 

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

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

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



5. H. subrhombpideus 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 solitary, rarely 2 or 

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

 acutish, white-ciliolate; ligules about 1.5 cm. long. Plains: Man. Ark. 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; ligules 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; ligules 12-20, 2.5-3.5 cm. long. Alluvial soil: N.S. Ga. Ark. 

 Neb. Sask. Plain. Au-O. 



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

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



