202 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Plants tall, 70 to 100 cm. high; fruiting bracts united 

 only at the base, triangular-ovate, few-toothed; 



leaves larger, 3 to 5 cm. long 2. 



Leaves ovate-lanceolate or triangular-ovate to subhastate; 

 branches mostly spreading. 



Bracts united only at the base 3. 



Bracts united to about the middle. 



Inflorescence tomentose as well as scurfy 4, 



Inflorescence merely scurfy. 



Leaves subcordate; scales loose and mealy. ... 5. 

 Leaves rounded or acute at the base; scales 

 appressed, somewhat silvery. 

 Leaves coarsely repand-toothed nearly 



throughout 6. 



Leaves toothed only near the base or 

 entire (subhastate). 



Leaves all excep t the lowest sessile 7 . 



Leaves all or nearly all conspicuously 

 petioled . 

 Bracts naked or with a few short 

 broad tubercles; some of the 

 leaves truncate at the base. 

 Bracts covered with long narrow 

 tubercles; all leaves nar- 

 rowed at the base 9. 



Perennials. 



Stems prostrate, slender; flowers monoecious 10. 



Stems erect, mostly stout; flowers mostly dioecious. 



Fruiting bracts united, completely surrounding the 

 seed, 10 mm. in diameter or more. 

 Bracts winged on the back and margin, forming a 

 4-winged pericarp, the margins shallowly if 



at all toothed 11. 



Bracts becoming thick and spongy, with numerous 



rigid teeth 12. 



Fruiting bracts united only at the base, 5 to 8 mm. in 

 diameter. 

 Stems woody, widely branched, spinescent; leaves 

 crowded . 

 Bracts rounded, entire; pistillate flowers stipi- 



tate; leaves rounded 13. 



Bracts acutish, dentate; pistillate flowers 



sessile; leaves mostly elliptic 14. 



Stems mostly herbaceous, woody only at the base, 

 not spinescent; leaves not crowded. 

 Fruiting bracts not crested (th^ck, not nerved); 



leaves 2 to 3 cm. long 15. 



Fruiting bracts crested on the back; leaves 

 small, 1 cm. long or less. 

 Bracts only slightly tuberculate; upper 



leaves very small; plants slender... 16. 

 Bracts densely covered with long narrow 

 appendages; all leaves large; plants 

 stout 17. 



A. wrightii. 



A. hastata. 

 A. powellii. 

 A. saccaria. 



A. rosea. 

 A. expansa. 



8. A. argentea. 



A. caput-medusae . 

 A. semibaccata. 



A. canescens. 



A. acanthocarpa. 



A. confertifolia. 

 A. collina. 



A. sabulosa. 



A. greggii. 

 A. cuneata. 



