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 to5cm.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 moncecious.............. 10. A. semibaccata. 
Stems erect, mostly stout; flowers mostly dicecious. 
Fruiting bracts united, completely surrounding the 
seed, 10 mm. in diameter or more. 
Bracts winged on the back and margin, forming a a 
4-winged pericarp, the margins shallowly if 
at all toothed....... we eee eee eee eens 11. A. canescens. 
Bracts becoming thick and spongy, with numerous 
rigid teeth...............-2-.---2-2-...000. 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 (thick, 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........... 2 ee ee eee ee eee eee 17. A. cuneata, 
