STANDLEY TREES AND SHRUBS OF MEXICO 1501 



Heads (at least the staminate) smaller, several to many, glomerulate or 

 panicled, rarely solitary at tips of branehlets, these arranged in 

 virgate racemes on the branches. 

 Heads solitary at tips of short branehlets, these arranged in virgate 



racemes on the branches 3. B. ramulosa. 



Heads otherwise. 



Heads panicled, very numerous, usually not overtopped by the 

 leaves. 



Pappus about 1 cm. long; receptacle naked ._.5. B. emoryi. 



Pappus about 3 mm. long; pistillate receptacle paleaceous. 



11. B. sergiloides. 

 Heads glomerulate at tips of branches or on short subterminal axil- 

 lary peduncles, usually overtopped by the leaves; pappus in 

 fruit 6 mm. long or less. 

 Leaves broadly cuneate or rhombic, 3 to 5-toothed, rarely entire, 



2 cm. long or less 7. B. conferta. 



Leaves elliptic, oval, obovate, or oblanceolate, the larger usually 

 more than 2 cm. long. 

 Leaves oblanceolate to cuneate-obovate, toothed or entire. 



8. B. heterophylla. 

 Leaves elliptic or oval, entire. 



Leaves 1.5 to 2.5 cm. long;Materal veins obsolete. 



9, B. vaccinioides. 

 Leaves 3 to 6 cm. long; lateral'veins finely prominulous beneath. 



10. B. lancifolia. 

 Leaves linear to narrowly oblanceolate, more than five times as long as wide. 

 Heads solitary at tips of densely foliose or bracteate branehlets, these 

 sometimes paniculately arranged. 



Larger leaves sharply toothed 3. B. ramulosa. 



Larger leaves entire. 



Floriferous branehlets covered with linear-oblanceolate or linear- 

 spat ulate leaves 1 mm. wide or less; staminate heads 3 to 5 mm. 



thick 12. B. ramiflora. 



Floriferous branehlets densely crowded with elliptic or oblanceolate 

 leaves 2 to 4 mm. wide; staminate heads 8 to 10 mm. thick. 



13. B. macrocephala. 



Heads usually paniculate or cymose, if solitary at tips of branches then 



on nearly or quite naked peduncles. 



Heads very numerous, in often elongate leafy panicles; pappus in 



fruit about 1 cm. long; leaves linear-oblanceolate to cuneate- 



oblanceolate, usually coarsely toothed. 



Main stem leaves linear-oblanceolate or narrowly oblanceolate, 



mostly 1-nerved 4. B. neglecta. 



Main ,^tem leaves cuneate-oblanceolate or oblong-oblanceolate, 



mostly triplinerved 5. B. emoryi. 



Heads solitary at tips of nearly naked branehlets or few and long- 

 peduncled, or in nearly naked cymes or panicles. 

 Heads 1 to 3, long-peduncled at tip of the subsimple stems. 



17. B. squarrosa. 

 Heads several to very many; stems usually much branched. 

 Plants finely and denseh' hirtellous or puberulous. 



18. B. brachyphylla. 



