1168 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



2. ASCLEPIAS L. Sp. PI. 214. 1753. 



Shrubs or usually herbs ; leaves opposite, verticillate, or alternate ; flowers 

 in terminal or axillary umbels ; calyx 5-parted ; corolla 5-parted, the lobes 

 valvate, reflexed in anthesis ; corona of 5 concave erect scales, each with a 

 terminal incurved hornlike terminal appendage ; follicles usually smooth ; seeds 

 with a terminal tuft of hairs. 



Numerous herbaceous species of milkweed occur in Mexico. 



Stems densely leafy, the leaves mostly scattered 1. A. linaria. 



Stems naked or nearly so except when young, the leaves opposite or verticillate. 



Corona scales 3 mm. long or less 2. A. albicans. 



Corona scales 6 to 7 mm. long 3. A. subulata. 



1. Asclepias linaria Cav. Icon. PL 1: 42. pi. 57. 1791. 

 Jalisco to Chihuahua, Veracruz, and Oaxaca. 



Stems herbaceous or more commonly woody, whitish-pubescent ; leaves 

 narrowly linear, 1 to 4 cm. long, glabrate; umbels axillary, pedunculate; 

 flowers green and white, the corona scales 2.5 to 3 mm. long; follicles ovoid 

 or narrowly ovoid, 3.5 to 6. cm. long, glabrous. " Romerillo " (Mexico, 

 Aguascalientes, San Luis Potosi) ; " plumerillo " (Aguascalientes) ; " torbisco " 

 (Duraugo) ; " mapipitza " (Mexico, San Luis Potosi, Ramirez); " Soliman " 

 (Mexico); " teperomero " (Mexico); " tlalayote " (San Luis Potosi, Mexico, 

 Vrbina) ; " venenillo " (Mexico, San Luis Potosi); " algodoncillo," " hierba 

 de la punzada " (Durango). 



The juice is used locally as a drastic purgative, but its use is dangerous. 

 Palmer reports that in Durango the leaves are applied to the temples to 

 relieve headache. 



2. Asclepias albicans S. Wats. Proc. Amer. Acad. 24: 59. 18S9. 



Baja California and Sinaloa ; type from Los Angeles Bay, Baja California. 



Stems numerous, often woody below, sometimes 3 meters high, whitish, 

 puberulent when young; "leaves opposite or ternate, linear, quickly deciduous; 

 corolla greenish white tinged with brown, the corona scales yellowish; 

 follicles slender, about 10 cm. long. 



3. Asclepias subulata Decaisne in DC. Prodr. 8: 571. 1844. 



Baja California, Sonora, and Sinaloa. Southern California and Arizona. 



Stems numerous, about 1 meter high, usually woody below, glabrous or nearly 

 so, glaucous ; leaves narrowly linear but quickly deciduous ; pedicels puberu- 

 lent ; corolla greenish white ; follicles slender, 10 to 12 cm. long. " Yamete " 

 (Baja California) ; " yumete " (Sonora) ; " candelilla bronca " (Sinaloa). 



The milky juice is sometimes employed as an emetic and purgative. 



3. ASTEPHANUS R. Br. Mem. Wern. Soc. 1 : 54. 1809. 



1. Astephanus pubescens Greenm. Proc. Amer. Acad. 32: 299. 1897. 



Morelos and Mexico ; type collected near Cuernavaca, Morelos, altitude 

 1,950 meters. 



Slender sufifrutescent vine, the stems pubescent ; leaves petiolate, lanceolate 

 or ovate-lanceolate, 1.5 to 6 cm. wide, acuminate, obtuse at base, pubescent ; 

 inflorescence subumbellate, few-flowered, the peduncles 1 to 2 mm. long, the 

 pedicels about 3 mm. long; calyx minute, 5-parted, pubescent; corolla sub- 

 campanulate, about 3 mm. broad, white or purplish, the lobes emarginate. 



