FLOWERING PLANTS AND FERNS OF ARIZONA 525 



13. Calyx 2- to 6-lobed; herbage with harsh, often stinging, hairs; 



plants slender and often twining 7. Tragia. 



13. Calyx 2-lobed; herbage glabrous (14). 



14. Plants herbaceous, sometimes woody at base; styles 3; 

 ovary and capsule 3-celled; staminate flowers solitary 



in the axil of each bract 12. Stillixgia. 



14. Plant a shrub; styles 2, rarely 3; ovary and capsule 2- or 

 rarely 3-celled; staminate flowers several in the axil of 

 each bract 13. Sapitjm 



1. REVERCHON1A 



Glabrous annual herb; leaves simple, alternate, entire, linear 

 spatulate to spatulate, petioled; stipules small, thin, ^ triangular- 

 subulate; flowers axillary, monoecious or dioecious; staminate sepals 

 4; stamens 2, the filaments free; pistillate sepals 6; glandular disk 

 present; ovary 3-celled; seeds not carunculate. 



1. Reverchonia arenaria A. Gray, Amer. Acad. Arts and Sci. Proc. 16: 

 107. 1881. 



Hopi Indian Reservation, Navajo County {Hough 39, Whiting in 

 1935). Utah and northeastern Arizona to Texas and northern 

 Mexico. 



This is supposed to be the only euphorbiaceous genus outside the 

 Australian region having the cotyledons no wider then the radicle. 

 Another unique feature is that the seeds are attached below the 

 middle rather than near the apex. The seeds are reported to be used 

 by the Hopi Indians in treatment of hemorrhage and also for oiling 

 their grinding stones. 



2. TETRACOCCUS 



Rigid divaricately branched shrub; leaves small, spatulate to 

 obovate-spatulate, petiolate, fascicled on very short lateral branch- 

 lets; flowers dioecious; staminate flowers 1 to 5 on the branchlets, 

 pedicelled, the sepals 5 or 6, the stamens 5 (in the limited material 

 examined from Arizona), the filaments distinct, attached around the 

 lobed central disk, a rudimentary pistil present; pistillate flowers 

 solitary on the short lateral branchlets, with short thick pedicels, the 

 ovary 3- or occasionally 4-celled, the styles 3 or occasionally 4, entire, 

 spatulate, the ovules 2 in each cell; seeds carunculate, mostly solitary 

 by abortion of 1 ovule and then dorsiventrally compressed, or later- 

 ally compressed when both seeds develop. 



1. Tetracoccus hallii T. S. Brandeg., Zoe 5: 229. 1906. 



Halliophytum hallii (T. S. Brandeg.) Johnston, Gray Her- 

 barium Contrib. 68: 88. 1923. 



Williams River near Alamo, Sheep Tanks, 1,850 feet, and Kofa 

 Mountains (Yuma County), along sandy washes, flowering in spring. 

 Southwestern Arizona and southeastern California. 



3. CROTON 77 



Herbs or shrubs; leaves alternate, petiolate, simple; stipules obso- 

 lete; flowers monoecious or dioecious; inflorescence racemose, the 

 staminate flowers above and the pistillate ones below in monoecious 



77 Reference: Ferguson, A. M. crotons of the united states. Mo. Bot. Gard. Ann. Rpt. 12: 

 33-73. 1901. 



