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. A. wrightii. 



Leaves ovate-lanceolate or triangular-ovate to subhastate; 

 branches mostly spreading. 



Bracts united only at the base 3. A. hastata. 



Bracts united to about the middle. 



Inflorescence tomentose as well as scurfy 4. A. powellii. 



Inflorescence merely scurfy. 



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



Leaves rounded or acute at the base; scales 

 appressed, somewhat silvery. 

 Leaves coarsely repand-toothed nearly 



throughout 6. A. rosea. 



Leaves toothed only near the base or 

 entire (subhastate). 



Leaves all except the lowest sessile 7. A . expansa. 



Leaves all or nearly all conspicuously 

 petioled . 

 Bracts naked or with a few short 

 broad tubercles; some of the 

 leaves truncate at the base. 8. A. argentea. 

 Bracts covered with long narrow 

 tubercles; all leaves nar- 

 rowed at the base 9. A . caput-medusae. 



Perennials. 



Stems prostrate, slender; flowers monoecious 10. A. semibaccata. 



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. A. canescens. 



Bracts becoming thick and spongy, with numerous 



rigid teeth 12. A. acanthocarpa. 



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 . A . confertifolia. 



Bracts acutish, dentate; pistillate flowers 



sessile; leaves mostly elliptic 14. A . collina. 



Stems mostly herbaceous, woody only at the base, 

 not spinescent; leaves not crowded. 

 Fruiting bracts not crested (thjck, not nerved); 



leaves 2 to 3 cm. long 15. A . sabulosa. 



Fruiting bracts crested on the back; leaves 

 small, 1 cm. long or less. 

 Bracts only slightly tuberculate; upper 



leaves very small; plants slender. ..16. A. greggii. 

 Bracts densely covered with long narrow 

 appendages; all leaves large; plants 

 stout 17. A. cuneata. 



