THISTLE FAMILY 895 



glandular-puberulent; ligules blue or bluish violet. M. paniculata A. Nels., a 

 large form. Mountains: Utah. Mont. Au. 



12. M. canescens (Pursh) A. Gray. Biennial; stem profusely branched, 

 1-4 dm. high; lower leaves spatulate or oblanceolate, slightly toothed; stem- 

 leaves linear, rarely narrowly oblanceolate, usually entire; heads numerous in 

 an open panicle; involucres 7-8 mm. high, about 1 cm. broad; ligules 8 mm. 

 long, dark bluish purple. A. canescens Pursh. M. magna A. Nels., a robust 

 form. Sterile ground and sandy banks: Sask. Colo. Calif. B.C. Plain 

 Son. Jl-S. 



13. M. superba A. Nels. Biennial; stem branched at the base; branches 

 ascending or decumbent, 8-15 cm. long; lower leaves oblong-oblanceolate, 4-6 

 cm. long, petioled; stem-leaves entire or remotely denticulate; involucres about 



8 mm. high, 1 cm. broad; ligules deep blue or purple, 8-10 mm. long. Sandy 

 hillsides: Wyo. Mont. Au. 



14. M. angustifolia Rydb. Biennial or perhaps perennial; stem about 1.5 

 dm. high, more or less tinged with purple; leaves linear, 2-5 cm. long and about 

 2 mm. wide, finely strigose-puberulent, sinuose-denticulate; involucres 7-9 mm. 

 high and broad; bracts oblong-lanceolate, acute, tinged with red or purple, com- 

 paratively thin; ligules 5-7 mm. long, rose or light purple. M. linearis Rydb., 

 not Greene. Sandy places: Wyo. Mont. Au. 



15. M. commixta Greene. Biennial; stem branched at the base; leaves 

 all spatulate, 3-6 cm. long, serrate, at least above the middle, 3-ribbed; heads 

 corymbose, large, about 1 cm. high and 12-15 mm. broad; ligules purple, about 



9 mm. long. Mountains: Utah. Submont. Mont. Jl-Au. 



16. M. leptophylla Rydb. Biennial, cespitose at the base; stem slender, 

 simple, 3-5 dm. high; lower leaves petioled, 2-5 cm. long, finely cinereous-puberu- 

 lent, in age sparingly so; blades spatulate or oblanceolate, thin; upper leaves 

 linear-oblanceolate or linear; involucre turbinate, 8 mm. high, 8-10 mm. broad; 

 ligules rose-purple, about 8 mm. long. Hills: Utah. Submont. Au. 



17. M. viscosa (Nutt.) Greene. Biennial; stem 3-5 dm. high; lower leaves 

 petioled, 4-7 cm. long, entire or somewhat toothed, oblanceolate; middle leaves 

 narrower and sharply serrate; involucres 8 mm. high, 10-12 mm. broad; ligules 

 purple, 8 mm. long. Hills, slopes, and plains: Mont. Wyo. Utah. Plain 

 Mont. Je-S. 



18. M. pulverulenta (Nutt.) Greene. Biennial; stem erect, 2-4 dm. high; 

 leaves narrowly oblanceolate, or the upper linear, 2-5 cm. long, entire or sparingly 

 denticulate; involucres 6-7 mm. high, 8-10 mm. broad, only slightly squarrose; 

 ligules purple, 7-8 mm. long. (?) M. subalpina Greene. Dry plains: Mont. 

 Colo. Utah Ida. Au-O. 



19. M. divaricata (Nutt.) Greene. Biennial; stem stout, about 3 dm. high; 

 branches numerous, more or less spreading; involucres turbinate, about 8 mm. 

 high, 10-12 mm. broad; ligules purple, nearly 1 cm. long. Hills and plains: 

 Mont. Wyo. Plain Submont. Au-O. 



20. M. glabella Greene. Biennial; stem 3-4 dm. high, glabrous; lower 

 leaves petioled, narrowly oblanceolate, glabrous, entire or slightly denticulate; 

 upper leaves narrowly linear; involucres turbinate, about 7 mm. high, 7-8 mm. 

 wide; ligules bluish purple, about 8 mm. long. M. pulverulenta vacans A. Nels. 

 Mountains: Colo. Submont. Mont. Jl-S. 



21. M. ramosa A. Nels. Biennial, branched at the base; stem ascending or 

 spreading, 2-4 dm. high; leaves green, nearly glabrous, linear-oblanceolate or 

 linear, the earlier sharply dentate; involucres hemispheric, about 7 mm. high 

 and 1 cm. wide; bracts linear, acute or short-acuminate, glandular-puberulent; 

 ligules purple, 8 mm. long. Mountains and plains: Wyo. Colo. Submont. 

 Mont. Jl-S. 



22. M. Selbyi Rydb. Biennial; stem often reddish, branched above; lower 

 leaves linear-oblanceolate to oblanceolate, petioled, glabrous or rarely slightly 

 puberulent, dentate; upper leaves linear; involucres hemispheric, 7-8 mm. high 



