STANDLEY TREES AND SHRUBS OF MEXICO. 749 



Ovules usually 3 in each cell ; flowers commonly smaller, nearly always less 

 than 2.5 cm. long. 

 Flowers axillary. 



Carpels rounded at apex. 



Stems long-hirsute S. A, h.irtum. 



Stems steUate-tomentose or pilosulous, never hirsute. 

 Leaves covered beneath with a very dense, minute, pale tomeutum. 



22. A. incanum. 

 Leaves green beneath, loosely stellate-pubescent. 



Petals about 1 cm. long; leaves long-acuminate 9. A. percaudatum. 



Petals 4 to 6 mm. long; leaves obtuse or acute 10. A. parvulum. 



Carpels narrowed at apex to a long or short beak. 



Stems hirsute 11. A. wrightii. 



Stems stellate-tomentose, never hirsute. 

 Peduncles viscid-pubescent. 

 Leaves with a closed basal sinus, the lobes overlapping. 



12. A. simulans. 



Leaves with an open sinus 13. A. dugesii. 



Peduncles without viscid pubescence. 

 Carpels of the fruit stellate-hirsute, at least above. 

 Carpels abruptly narrowed into a very short beak. 



14, A. glabrifl^orum. 

 Carpels gradually narrowed to a long beak. 

 Carpels about 1.5 cm. long ; leaves green above, whitish beneath. 



15. A. hypoleucum. 

 Carpels about 1 cm. long; leaves nearly concolorous. 



35. A, aurantiacum. 

 Carpels finely stellate-tomentose. 



Carpels abruptly short-pointed 16. A. sphaerostaminum. 



Cari^els gradually long-pointed. 



Sepals equaling or longer than the carpels 17. A. lignosum. 



Sepals shorter than the carpels 18. A. californicum. 



Flowers chiefly in umbels, panicles, or racemes. 



Carpels rounded or obtuse at apex, very shortly or not at all beaked. 

 Carpels 4 or 5. 



Calyx 10 to 12 mm. long 19. A. bastardioides. 



Calyx 4 to 7 mm. long. 



Calyx nearly as long as the carpels, erect 20. A. malacum. 



Calyx less than half as long as the carpels, spreading or reflexed. 



Cancels short-beaked; stems trigonous 21. A. trisulcatum. 



Carpels usually not beaked ; stems usually terete. 



22. A. incanum. 

 Carpels more than 5, usually 8 or more. 



Stems pilose with very long spreading hairs 23. A. sonorae. 



Stems stellate-tomentose or short-pilose. 



Flowers umbellate 24. A. discolor. 



Flowers in large panicles. 

 Stems glabrate ; calyx lobes broadly ovate, obtuse. 



25. A, reventum. 



Stems densely tomentose or tomentulose; calyx lobes ovate, acute. 



Stems minutely tomentose; calyx less than half as long as the 



carpels 26. A. andrieuxii. 



Stems loosely tomentose ; calyx nearly as long as the carpels. 



27. A. xanti. 



