﻿182 Vail: Studies in the Asclepiadaceae 



7. Asclepias Mexicaxa Cav. Ic. 1 : 42. pi. 38. 1791. 



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This species is a tall, stout, branched plant, woody at the base, 

 from a short rootstock, with linear-lanceolate, spreading leaves, 

 which are whorled in 3-5's, acute at each end, with ascending 

 veins. In some specimens the upper leaves are plicate and fal- 

 cately drooping. Inflorescence cymosely terminal and often nu- 

 merous umbels in two or three of the lower axils. The umbels 

 are about twice or more larger than those of A. verticillata and in 

 some cases a little smaller than those of A. galioides. The flowers 

 are also commonly more numerous than in either of the foregoing 



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species, the corolla-segments are ash-colored and the hoods white; 



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the ventral margins of the latter are rounded and without the dis- 

 tinct angle or lobe of A. vsrticillata and with a somewhat shorter 

 horn. The follicles are slightly larger and less slender and the 

 plant usually fruits more abundantly than those of A. verticillata. 

 A species common in the Western States and which varies 

 greatly in the size of the leaves and the color of the flowers. 

 Smaller, more slender forms have been collected in eastern Ore- 

 gon by F. E. Lloyd ; in Lake County, California, by Mrs. O'Neil, 

 apparently growing with the type ; they are probably only young 

 plants. Another quite remarkable form, with uniformly shorter, 

 very coriaceous leaves, comes from Mexico, where it has been 

 collected by Pringle, no 2574, as to specimen in Herb. Columbia 



University. 





