1488 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



Plant not tomentose. 



Leaves cuneate to linear-elliptic, 7 times as long as wide orl ess. 

 Leaves cuneate to obovate, 2 cm. long or less. 



3. A. cuneatus spathulatus. 

 Leaves linear-elliptic to obovate, 2.5 to 6 cm. long. 



Heads in a virgate panicle; involucre 7 to 9 mm. high, strongly 



graduate, many-seriate 23. A. orcuttii. 



Heads in a flattish terminal corymbiform panicle; involucre 5 mm. 



high, few-seriate 11. A. parishii. 



Leaves linear to linear-spatulate, more than 8 times as long as wide. 

 Involucre 5 to 7 mm. high, the middle phyllaries acute and with 



definite green tips 20. A. fasciculatus. 



Involucre 5 mm. high or less, the middle phyllaries obtuse or rarely 



acute, without definite greenish tips 15. A. heterophyllus. 



Leaves toothed or pinnatifid. 



Plant tomentose 21. A. canus. 



Plant not tomentose. 



Involucre 12 to 15 mm. high, the phyllaries oblong-linear, appressed, 

 without loose green tips. 

 Leaves oval or oblong-obovate, with broad clasping base. 



24. A. berberidis- 



Leaves cuneate-obovate, narrowed to the base 25. A. cruentus. 



Involucre 10 mm. high or less. 



Heads solitary at tips of stem and branches. 



Stem and leaves essentially glabrous, resinous; involucre 4.5 mm. 

 high, the outer phyllaries ciliate, not glandular-granular. 



13. A. vernicosus. 

 Stem and leaves glandular-granular or pubescent; involucre 5 to 

 10 mm. high, the phyllaries not ciliate, densely glandular- 

 granular. 

 Leaves obovate or cuneate-obovate, merely toothed, obtuse, 

 nearly uniform in shape; phyllaries with spreading or 

 reflexed herbaceous tips 1.5 to 2 mm. long; plant very 



densely glandular-pubescent 28. A. arenarius. 



Leaves linear to obovate, usually acute, at least the lower usually 

 pinnatifid, the upper usually different in shape and toothing 

 from the lower; herbaceous tips of the phyllaries appressed or 

 short and spreading. 

 Plant dull green or cinereous, densely glandular-pubescent or 

 hispid-pilose; upper and branch leaves mostly oblong- 

 linear or oblanceolate, toothed. 



26. A. spinulosus scabrellus. 

 Plant bright light green, sparsely glandular-granular; upper 

 and branch leaves linear, entire or toothed. 



27. A. junceus. 

 Heads closely cymose or virgate-panicled. 



Heads small, few-flowered, 5.5 mm. high or less; leaves 1 cm. long 



or less 13. A. vernicosus. 



Heads larger, many-flowered; leaves more than 1 cm. long. 

 Heads in elongate, virgate or pyramidal panicles. 

 Stem rough-pubescent; leaves sharply toothed. 



22. A. squarrosus. 

 Stem essentially glabrous; leaves merely denticulate. 



23. A. orcuttii 



