MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



Key to the species 

 1. Heads 3- to 5-flowered (2) . 



2. Leaves linear-lanceolate, elongate, 3 to 13 cm. long, 2 to 10 mm. wide. 



1. B. LONGIFOLIA. 



2. Leaves lance-ovate, 12 to 28 mm. wide 2. B. multiflora. 



1. Heads (6) 8- to 60-fiowered (3). 



3. Plant with abundant very short budlike branchlets bearing minute, crowded, 



4-ranked, scalelike leaves; stem leaves (mostly deciduous) narrowly 



linear, entire, 3 to 7 cm. long, 2 mm. wide or less — 3. B. squamulosa. 



3. Plant without budlike branchlets bearing crowded scalelike leaves; stem 



leaves persistent, linear to broadly ovate, more than 2 mm. wide (4) . 



4. Leaves linear to elliptic or lance-ovate, cuneate to rounded at base, 



subsessile or on petioles 3 mm. long or less (5). 



5. Heads about 40- to 50-flowered, solitary, or few and cymose; leaves 



elliptic-ovate to lance-linear, usually entire 9. B. oblongifolia. 



5. Heads 9- to 26-flowered, numerous, panicled (6). 



6. Leaf blades 5 to 12 mm. long, lanceolate to ovate; achenes finely 

 hispidulous; heads mostly solitary at the tips of slender, minutely 

 leafy peduncles, forming a long racemiform panicle. 



4. B. SCABRA. 

 6. Leaf blades usually 20 to 60 mm. long; achenes densely pubescent; 

 heads otherwise arranged (7) . 

 7. Pappus bristles plumose; leaves lanceolate or lance-ovate. 



5. B. BRACHYPHYLLA. 



7. Pappus bristles not at all plumose; leaves linear to oblong or lance- 

 oblong, rarely lanceolate (8). 

 8. Phyllaries few (about 14); heads about 10-flowered. 



6. B. LEMMONI. 

 8. Phyllaries numerous (20 to 37) ; heads usually 19- to 26-flowered 

 (9). 

 9. Plant glandular-pubescent, especially above; leaves narrowly 



lanceolate, 12 to 15 mm. wide 13. B. amplexicaulis. 



9. Plant not glandular-pubescent (10). 



10. Heads slender-pedicelled, in a loose panicle; leaves linear 

 or narrowly linear-oblong, 3 to 9 mm. wide. 



7. B. VENOSA. 



10. Heads sessile or subsessile, subspicate on the stem and 



branches; leaves elliptic, oblong, or lance-oblong, 8 to 



20 mm. wide 8. B. pringlei. 



4. Leaves definitely ovate or rhombic-ovate or, if lance-oblong, then with 

 distinctly cordate-clasping base (11). 

 11. Leaves coriaceous, bright green, spinj^-toothed; outer phyllaries herba- 

 ceous or subcoriaceous, much broader than the inner and nearly 

 as long; heads solitary at the tips of the branches, about 50-flowered. 



10. B. ATRACTYLOIDES. 



11. Leaves not coriaceous (except in B. baccharidea) , not spiny-toothed; 



outer phyllaries not noticeably broader than the inner, much 



shorter; heads panicled, except in B. simplex and B. incana (12). 



12. Leaves (at least when young) and stem densely white-tomentose ; 



leaves small, ovate, sessile; heads about 60-flowered, about 23 



mm. high, solitary at tips of stem and branches. 



11. B. INCANA. 



12. Leaves and stem not densely white-tomentose, if grayish-tomentel- 

 lous (B. desertorum) , then the heads 8- to 12-flowered (13). 

 13. Leaves lance-oblong to ovate, sessile or very short-petioled, 

 strongly cordate at base (14). 

 14. Leaves ovate or oblong-ovate, distinctly short-petioled; pedicels 

 hispidulous or short-hirsute, not glandular. 



12. B. BETONICAEFOLIA. 



14. Leaves lance-oblong or ovate-oblong, sessile, strongly cordate- 



clasping; pedicels densely stipitate-glandular. 



13. B. AMPLEXICAULIS. 



13. Leaves ovate or rhombic-ovate, usually slender-petioled (15). 



15. Blades of the largest leaves 12 mm. long or less; leaves green; 



heads mostly solitary at the tips of the slender, minutely 

 leafy branches, forming a long racemiform panicle. 



4. B. scabra. 



