663 



Vail : Studies in the Asclepiadaceae 



I. Rouliniella unifaria (Scheele) 

 Gonolobus miifarius Scheele, Linnaea, 21 : 760. 



1848. 



Roidinia unifaria Engelm. Mex. Bound. Surv. 160. 1850. 



A slender climbing and twining vine. Stems pale gray-green 

 when fresh, striate, glabrous or minutely pubescent in lines on the 

 upper portion and somewhat sulcate : leaves opposite, on petioles 

 1-4 cm. long ; blades 3-7 cm. long, ovate, somewhat hastately cor- 

 date, gradually acuminate, glabrous, thin, the auriculate basal 

 lobes rounded, with a broad open sinus and a few glands at the 

 base of the midvein above : peduncles longer than the petioles 

 and as long as or exceeding the leaves : racemes as long or longer 

 than the leaves, 7-12-flowered : rhachis minutely pubescent or 

 puberulent in lines : flowers globose in bud : pedicels stout, i cm. 

 long or^iess, pubescent : calyx-.segments lanceolate-oblong, 4 mm. 

 long, with a gland in each 

 sinus : corolla 4-6 mm. long, 

 white ; segments 3 mm. long, 

 linear-oblong, 2.5 mm. wide, 

 broadly obtuse or nearly trun- 

 cate, thin, 3 -veined, the callous 

 thickened margins revolute ; 

 crown attached to the base of 

 the column, 5 -parted to near 

 the base ; segments erect, not 

 exceeding the anthers, min- 

 utely 3-lobed, the middle one 

 slightly the longest, the lateral 

 lobes with thin infolded margins at the base within : anther- 

 wings small ; anther-tips semi-orbicular, inflexed on the scarcely 

 conic stigma: pollinia elliptical -ovoid ; caudicles broad at the 

 attachment, orange-red on the upper margin ; corpuscle obtuse at 

 the apex : follicles 6 cm. long, ovate, acuminate with an obtuse 

 apex, coriaceous, glabrous : seeds 5 mm. long : coma i cm. long. 

 {Fig. /.) 



Type locality: On the Upper Guadeloupe River, near New 



Braunfels, Texas. Thickets, Kerr county, Texas, to " Mts. of 



Muerte," New Mexico. Wright ; western Texas to El Paso, 



Wright, 5-1-6 ; near Kerrville, Heller, iSgg (distributed as Am- 



pelanus ligulata) ; Mexican Boundary Survey, no. lo^g. 



The specimens cited by Hemsley, for Roidinia imifaria from 

 " North of Monclova, Coahuila," Palmer, 82g are Roidiniella Pal- 



FlG. I. 



