Genus 6. 



MILKWEED FAMILY. 



37 



6. VINCETOXICUM Walt. Fl. Car. 104. 1788. 

 Twining or trailing perennial vines, with opposite usually cordate leaves, and rather large 

 purple, brown, white or greenish flowers in axillary cyme-like umbels or fascicles. Calyx 

 S-parted or deeply S-cIeft, mostly 5-glandular within. Corolla rotate, very deeply 5-parted, 

 the tube very short, the segments convolute in the bud. Corona (crown) annular or cup- 

 shaped, entire, lobed or divided, adnate to the corolla. Stamens inserted on the base of the 

 corolla, the filaments connate into a tube ; anthers not appendaged, merely tipped, borne along 

 or just under the margin of the flat-topped stigma, the sacs more or less transversely dehis- 

 cent. Pollen-masses solitary in each sac, horizontal or nearly so. Follicles thick, acuminate, 

 smooth, angled or tuberculate. Seeds comose. [Greek, subduing poison.] 



About 75 species, natives of America. Besides the following, some 10 others occur in the 

 southern and southwestern United States. Type species : Vincetoxicum gonocarpos Walt. 



Crown annular, 10-crenate: follicles angled, not warty. 



Corolla about twice as long as the calyx. 1. V. suberosum. 



Corolla 3-4 times as long as the calyx. 2. V. gonocarpos. 



Crown cup-shaped, about as high as the anthers; follicles warty. 

 Flowers purple to dull yellow. 



Corolla-segments oblong, 3"-4" long; crown crenate. 3. I'.hirsutum. 



Corolla-segments linear or linear-oblong, 5" 7" long. 



Crown merely crenate. 4. V. obliquum. 



Crown toothed or lobed. 



Crown 5-lobed, with a subulate 2-cIeft tooth in each sinus. 5. V. carolinense. 



Crown 10-toothed, the alternate teeth thinner and longer. 6. V.Shortii. 



Flowers white ; crown deeply cleft. 7. V.Baldwinianum. 



i. Vincetoxicum suberosum (L.) Critton. Coast Vincetoxicum. Fig. 3416. 



Cynanchum suberosum L. Sp. PI. 212. 1753. 



G. suberosus R. Br. in Ait. Hort. Kew. Ed. 2: 82. 1811. 



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



Stem pubescent or glabrous, slender, twining. 

 Leaves thin, 2'-s' long, i'-t,' wide, ovate or ovate- 

 oval, acute or abruptly acuminate at the apex, cor- 

 date at the base; petioles -2 long; umbels com- 

 monly few-flowered ; peduncles i'-i' long ; pedicels 

 J'-l' long, fleshy, nearly glabrous ; corolla brown- 

 purple, broadly conic in the twisted bud, its segments 

 lanceolate or ovate-lanceolate, acute, pubescent or 

 granulose within, 3"-4" long, about twice as long as 

 the calyx ; crown an annular fleshy undulately 

 10-crenate disk ; follicles glabrous, 3-5-angled, when 

 young fleshy, when mature dry and spongy, 4'-6' 

 long, 1' in diameter or more. 



In thickets, Virginia to Florida, mainly near the coast. 

 May-July. 



2. Vincetoxicum gonocarpos \\'alt. Large- 

 leaved Angle-pod. Fig. 3417. 



Vincetoxicum gonocarpos Walt. Fl. Car. 104. 1788. 

 G. macrophyllus Michx. Fl. Bor. Am. 1 : 119. 1803. 

 Gonolobus laevis var. macrophyllus A. Gray, Syn. Fl. 2: 

 Part 1, 103. 1878. 



Glabrous or pubescent, stems slender, climbing 

 high. Leaves broadly ovate, thin, 3'-%' long, 2'-6' 

 wide, acuminate at the apex, deeply cordate at the 

 base, the sinus narrow or the rounded auricles over- 

 lapping; petioles 1-4' long; umbels few-flowered; 

 peduncles i'-3' long; pedicels rather stout, glabrous 

 or nearly so ; corolla conic in the bud, not twisted, its 

 segments lanceolate, glabrous, 4,"-$" long, 3-4 times 

 as long as the calyx ; crown a low obtusely undulate 

 disk; follicles glabrous, similar to those of the pre- 

 ceding species but usually shorter. 



Along rivers and in moist thickets, Virginia to South 

 Carolina, Georgia, Indiana Missouri and Texas. 



