ASCLEPIADACEAE. 



VOL. III. 



3. Vincetoxicum hirsutum (Michx.) Britton. 

 Hairy Vincetoxicum. Fig. 3418. 



Gonolobus hirsntus Michx. Fl. Bor. Am. i : 119. 1803. 

 V, hirsutum Britton, Mem. Torr. Club 5 : 266. 1894. 



Stem downy, slender. Leaves ovate, acuminate at 

 the apex, deeply cordate at the base, downy, 2'~4' 

 long, i'-2i' wide, the sinus narrow, or the lobes 

 sometimes overlapping; petioles slender, pubescent, 

 i'-2' long; peduncles usually about equalling the 

 petioles, sometimes longer ; umbels few-several- 

 flowered; corolla brown-purple to greenish yellow, 

 ovoid in the bud, its segments oblong, very obtuse, 

 3 "-4" long, minutely puberulent without, about 4 

 times as long as the densely pubescent calyx ; crown 

 cup-shaped, fleshy, about as high as the anthers, the 

 margin lo-crenate ; follicles lanceolate, 3'-$' long, 

 muricate, puberulent ; seeds entire. 



In thickets, Maryland to Florida, west to Tennessee. 

 Running milkweed. Negro-vine. July-Aug. 



4. Vincetoxicum obliquum (Jacq.) Britton. 



Fig. 34I9- 



Cynanchum hirtum L. Sp. PI. 212. 1753? 

 Cynanchum obliquum Jacq. Coll. i : 148. 1786. 

 G. obliquus R. Br. ; R. & S. Syst. 6 : 64. 1820. 

 V. obliquum Britton, Mem. Torr. Club 5: 266. 1894. 



Stem puberulent or hirsute, slender. Leaves 

 pubescent, broadly ovate, short-acuminate at the 

 apex, deeply cordate at the base with an open or 

 closed sinus, 2'-8' long, rJ'-6' wide; petioles 

 rather stout, pubescent, i'-4' long; umbels slen- 

 der-peduncled, few-several-flowered ; pedicels very 

 slender, i'-2 r long; corolla narrowly conic in the 

 bud, red-purple within, greenish and minutely 

 pubescent without, its segments elongated-linear, 

 obtuse, 6-7 times as long as the hirsute calyx ; 

 crown cup-shaped, as high as the anthers, fleshy, 

 its margin lo-crenulate, the intermediate crenu- 

 lations sometimes 2-dentate; follicles ovoid-lan- 

 ceolate, a'-3' long, muricate. 



In thickets, Pennsylvania to Ohio, Missouri, Vir- 

 ginia and Kentucky. July-Aug. 



Large-flowered Vincetoxicum. 



5. Vincetoxicum carolinense (Jacq.) Britton. 

 Carolina Vincetoxicum. Fig. 3420. 



Cynanchum carolinense Jacq. Coll. 2: 228. 1788. 

 G. carolinensis R. Br. ; R. & S. Syst. 6 : 62. 1820. 

 V. carolinense Britton, Mem. Torr. Club 5: 265. 1894. 



Stem hirsute. Leaves broadly ovate, acute or 

 short-acuminate at the apex, deeply cordate at the 

 base with a narrow or closed sinus, 3'-/' long, 2'-$' 

 wide, pubescent, at least beneath ; petioles hirsute, 

 ii'-4' long; peduncles 2'~4' long; pedicels very slen- 

 der, i' long or more ; corolla brown-purple, oblong- 

 conic in the bud, puberulent without, its segments 

 linear-oblong or linear-lanceolate, obtusish, 5''-6" 

 long, 5-6 times longer than the hirsute calyx ; crown 

 cup-shaped, scarcely fleshy, 5-lobed, with a subulate 

 longer 2-cleft erect tooth in each sinus ; follicles 

 muricate. 



In thickets, Virginia to Missouri, south to South Caro- 

 lina and Louisiana. May-July. 



