WOOTON AND STANDLEY FLORA OF NEW MEXICO. 397 



5. ZYGOPHYLLIDIUM Small. 



Annuals with erect branching stems; leaves opposite, or rarely alternate below, not 

 oblique at the base, entire; stipules glandlike, often obsolete; involucres delicate, 

 short-pedunculate in the upper forks of the stems; glands 5, broader than long, sub- 

 tended by petal-like appendages; capsules long-pediceled, 3-lobed; seeds terete, 

 usually narrowed upward, more or less papillose, the caruncle sometimes wanting. 



KEY TO THE SPECIE.S. 



Plants glabrous; upper leaves ovate, long-petioled 1. Z. delicatulum. 



Plants more or less pubescent; upper leaves linear or oblong- 

 linear. 



Glands bilobate; seeds not carunculate 2. Z. hilohatum. 



Glands entire; seeds carunculate 3. Z. exsiipulatum. 



1. Zygophyllidiiiin delicatulum Woot. & Standi. Contr. U. S. Nat. Herb. 16: 145. 



1913. 



Type locality: Mineral Creek, Sierra County, New Mexico. Type collected by 

 Metcalfe (no. 1414). 



Range: Mountains of southern New Mexico. 



New Mexico: Black Range; White Mountains. Transition Zone. 



A very different plant from any of the other species of the genus, differing most 

 noticeably in the width and shape of the leaf blades and in the glabrous involucres. 



2. Zygophyllidiuni bilobatum (Engelm.) Standley, Contr. U. S. Nat. Herb. 13: 



199. 1910. 

 Euphorbia bilobata Engelm. in Terr. U. S. & Mex. Bound. Bot. 190. 1859. 

 Type locality: Near the Copper Mines, New Mexico. Type collected by Bigelow. 

 Range: New Mexico and Arizona. 



New Mexico: MogoUon Mountains to the Organ Mountains and southward. Hills 

 and caayons, in the Upper Sonoran Zone. 



3. Zygophyllidiuni exstipulatum (Engelm.) Woot. & Standi. Contr. U. S. Nat. Herb. 



16: 146. 1913. 

 Euphorbia exstipulata Engelm. in Torr. U. S. & Mex. Bound. Bot. 189. 1859. 

 Type locality: Western Texas. 



Range: Western Texas to southern Arizona and adjacent Mexico. 

 New Mexico: Stanley; Tortugas Mountain; Kingston; plains between Fort Win- 

 gate and Beleu; Carrizozo; Apache Teju. Lower and Upper Sonoran zones. 



6. CHAMAESYCE S. F. Gray. Spurge. 



Annual or perennial herbs, mostly branching from the base; branches erect, ascend- 

 ing, or prostrate; leaves opposite, the blades entii'e or toothed, more or less oblique 

 at the base; stipules delicate, entire or fimbriate; involucres axillaiy, solitary or in 

 cymes; glands 4, sessile or stalked, naked or usually appendaged, one sinus glandless; 

 capsules smooth, sometimes pubescent, the angles sharp or rounded; seeds smooth 

 or transversely wrinkled, with minute caruncles. 



The different species are known among the Mexicans as "golondrina." The plants 

 are reputed, everywhere in the Southwest, to be a remedy for rattlesnake bites. 



KEY TO THE SPECIES. 



Leaf blades toothed, at least near the apex. 

 Capsules pubescent. 



Glands of -the involucre with conspicuous petal-like ap- 

 pendages 1 . C. indivisa. 



Glands of the involucre with small and inconspicuous 



appendages 2. C. stictospora. . 



