THISTLE FAMILY 875 



12. T. scapigera D.C. Eat. Cespitose, almost acaulescent perennial ; leaves 

 2-4 cm. long, sparingly strigose; blades spatulate; stem 2-5 cm. high, scapiform; 

 involucres alaout 10-15 mm. wide; bracts oblong-lanceolate, in 3 series, acute, 

 strigose on the back, with rather narrow, pinkish, scarious, erose margins; ligules 

 bluish purple, about 1 cm. long; pappus of both ray- and disk-flowers of many 

 bristles. High mountains: Mont. — Wyo. — Calif. Submont. — Mont. My-Jl. 



13. T. incana Nutt. Cespitose perennial; stems 1-10 cm. high, canescent- 

 hirsute; leaves linear-oblanceolate, canescent-strigose, 2-3 cm. long; heads sessile; 

 involucres 8 mm. high, about 1 cm. wide; bracts lanceolate, acute, densely stri- 

 gose, scarious and erose on the margins; ligules lilac, 8 mm. long. Mountains 

 and hills: Wyo.— N.M.— Ariz.— Utah. Son.—Subalp. My-Je. 



14. T. arizonica A. Gray. Cespitose perennial, tufted; stems 3-8 cm. long, 

 sericeous-canescent; leaves spatulate, 1-2 cm. long, long-petioled ; involucres 

 10-12 mm. broad; bracts lanceolate, obtuse, strigose on the back, scarious and 

 erose-ciliate on the margins; ligules 5-8 mm. long; pappus of all the flowers of 

 the same length, rather rigid, about as long as the achenes. Hills: Utah — Ariz. 

 Son. 



15. T. glabella A. Gray. Cespitose perennial; stems 2-5 cm. high, spar- 

 ingly strigose; leaves spatulate, 2-3 cm. long; involucres 10-12 mm. broad; bracts 

 lanceolate, in 2 or 3 series, acute, green, only slightly scarious-margined, ciliate; 

 pappus of the ray-flowers about one-fourth as long as that of the disk-flowers or 

 less. T. Bakeri Greene. Mountains: Colo. Subalp. — Mont. My-Jl. 



16. T. Rothrockii A. Gray. Acaulescent pulvinate perennial; leaves spatu- 

 late, 2-3 mm. long, rosulate; involucres 8 mm. high, 1-2 cm. broad; bracts oblong, 

 obtuse, glabrous, purple-tinged, scarcely scarious-margined, ciliate. High moun- 

 tains: Colo. Submont. — Mont. Jl. 



17. T. Wilcoxiana Wood. Cespitose acaulescent perennial; leaves narrowly 

 linear-oblanceolate. 3-7 cm. long, glabrous above, sparingly pubescent beneath; 

 involucres 1.5-3 cm. broad; bracts acute, lanceolate, tinged with purple, scarcely 

 scarious-margined; ligules 10-15 mm. iong. Plains and hills: Okla. — Colo. 

 Plain. Ap-Je. 



18. T. intermedia Rydb. Acaulescent cespitose perennial ; leaves oblanceo- 

 late, mostly acute; involucres 1.5-3 cm. broad; bracts narrowly lanceolate, in 

 4 or 5 series. Dry soil : Neb. — Ivans. — Ariz. — Wyo. Plain. Ap-My. 



19. T. leptotes (A. Gray) Osterh. Cespitose perennial, mostly acaulescent; 

 leaves linear-oblanceolate, sparingly strigose; heads mostly sessile; involucres 

 1 cm. broad; bracts linear, rounded on the back, ciliate on the margins, but not 

 scarious. T. sericea leptotes A. Gray. Mountains: Colo. Je. 



20. T. exscapa (Richards.) Porter. Cespitose acaulescent perennial; leaves 

 sericeous-strigose, 2-5 cm. long; involucres 1 cm. high, 1-3 cm. broad; bracts 

 narrowly lanceolate, in 4 or 5 series; achenes hirsute; pappus-bristles of the disk- 

 flowers twice as long as the achenes, those of the ray-flowers often shorter. T. 

 sericea Hook. T. mensana M. E. Jones. Plains: Sask. — Tex. — N.M. — Alta. 

 Plain — Mont. Ap-Je. 



21. T. spathulata Nutt. Cespitose, acaulescent, multicipital perennial; 

 leaves crowded, spatulate, densely villous-lanate ; heads sessile; involucres 8 mm. 

 high; bracts oblong-lanceolate, acute; rays short, pinkish; pappus of the ray- and 

 disk-flowers similar, of many bristles. High mountains: Wyo. 



31. BRACHYACTIS Ledeb. 



Leafy-stemmed annuals, with entire leaves. Heads rather small, numerous, 

 paniculate. Involucres campanulate; bracts in 2-3 series, linear or oblong, 

 almost equal in length, the outer foliaceous and loose. Ray-flowers in several 

 series, more numerous than the disk-flowers, white, shorter than the pappus, with 

 short or no ligule. Disk-flowers perfect, with slender, 4-5-toothed corollas. 

 Style-branches with lanceolate appendages. Achenes narrow, not compressed, 

 2-3-nerved, appressed-pubescent. 



