﻿176 Vail : Studies in the Asclepiadaceae 



more crowded and scattered, and numerous and small umbels of 

 white flowers which are solitary or corymbosely disposed at the 

 summit of the stems. This species occurs on dry plains from 

 South Dakota to Arkansas, Colorado and New Mexico. It may 

 possibly intergrade with A. verticillata, but a long series of 

 specimens are constant to the above characters. 



des H.B.K. Nov. Gen. etSpec. 3: 188. 1818. 



Asclep 



A. Gray, Proc. Am 



Acad. 12: 71. 1876. In part. 



Glabrous except for the minutely pubescent stems and pedicels. 

 Stems erect, solitary or fasicled ? from a sometimes long horizontal 

 rootstock, 4—10 dm. high or more, glabrous or minutely pubes- 

 cent in lines above, simple or branched : leaves commonly erect or 

 spreading, in whorls of 3-6 ; blades narrowly linear, 6-8 or pos- 

 sibly 10 cm. long, 1-2.5 mm - wide, usually coriaceous; margins 

 entire or revolute ; midvein conspicuous beneath and the veins ob- 

 solete : inflorescence cymosely terminal or often many of the 

 umbels also lateral : peduncles longer than the 1 cm. long pedicels 

 and shorter than the leaves : umbels 2-3 cm. in diameter : corolla- 

 segments greenish white, oblong, obtuse, 4 mm. long : column 

 nearly 1 mm. high, slender : hood nearly reaching the summit of 

 the anthers, erect-spreading, broadly rounded at the apex, the dor- 

 sally hastate-sagittate ventral margins slightly involute, entire ; horn 

 arising from the base of the hood, flat, long-exserted and somewhat 

 inflexed over the anthers : anther-wings slender, minutely notched 

 at the angled base : follicles 5-7 cm. long, glabrous or minutely 

 puberulent, acute or attenuate above : seeds 5-6 mm. long, thin, 

 glabrous; coma 2.5 cm. long. 



Kansas: Popinoe, no. 34, 1875. Colorado: Eastwood. New 

 Mexico : Lieut. Abert ; Wright, low grounds, near San Elizario, 

 i° to 3 high, June 14th, no. 1685, nos. 1688 and 1689, 1852; 



Fendler, no. 694; Rothrock, no. 77^ Vasey; Dewey; Manson 



and Hopkins, 1889. Arizona: Tourney, no. 248; Lemmon ; 

 Knowlton, nos. 219 and 224; M. E. Jones, no. 4063; Rusby, 

 1883 ; Palmer ; MacDougal, no. 386; Mexican Boundary Survey, 

 no. 1078. Mexico: Hartweg, no. 216; Schaffner, no. 59; So- 

 nora Valley, Schott ; Parry and Palmer, no. 584; Palmer, no. 

 809 ; Parras, Gregg ; Edwards. 



specimens 



