952 ASCLEPIADACEAE 



deeply cordate with rounded basal lobes, palmately veined, glabrous or nearly so above, 

 the veins minutely pubescent beneath, midvein with a small cluster of subulate glands at 

 the base above : cymes usually numerous, rather densely many-flowered, not exceeding the 

 petioles : pedicels 4-5 mm. long : corolla-lobes ovate, 4 mm. long, linear-lanceolate, acutish 

 with reflexed tips : crown-lobes ovate, barely truncate, the slender awns nearly as long as 

 the corolla-lobes : anther-tips conspicuous, cordate at the base : follicles erect on spreading 

 pedicels, 10-15 cm. long, glabrous, wing-angled : seeds 9-10 mm. long, thin, crenate at the 

 apex : coma 4 cm. long. [Enslenia albida Nutt. ] 



On river banks and in thickets, southern Pennsylvania to Kansas, Florida and Texas. Summer. 



11. SEUTERA Reichenb. 

 Slender twining vines. Leaves mostly opposite : blades narrowly linear. Flowers in 

 peduncled umbels. Calyx small : lobes 5, acute, with a gland in each sinus. Corolla sub- 

 rotate : lobes 5, spreading, acuminate. Crown adnate to the short column below the 

 anther-wings, united at base : lobes merely notched at the apex. Anther-wings corneous, 

 angled at the base. PoUinia pendulous. Stigma conic, obscurely bifid. Follicles smooth, 

 slender, essentially terete. 



1. Seutera paliistris (Pursh) Vail. Stems filiform, herbaceous, glabrous, freely 

 twining over grasses and low bushes : leaves 2-7 cm. long ; blades linear, somewhat fleshy, 

 acute, glabrous, pendent : peduncles commonly longer than the leaves : umbels several- to 

 many-flowered : calyx-lobes lanceolate, acute : corolla purplish or greenish white, 3-4 cm. 

 long ; lobes ovate-lanceolate, acuminate : crown 5-lobed, adnate to the summit of the very 

 short column ; lobes oblong-obovate, entire, retuse or emarginate at the apex, about one 

 half the length of the corolla : anthers sagittate at base : poUinia oblong-elliptical in out- 

 line on rather broad, stout caudicles : follicles slender-fusiform, acuminate, 5 cm. long, 

 glabrate : seeds 3-3.5 mm. long, very thin, glabrous : coma 2 cm. long. l_S. maritima 

 Decne. ] 



In salt marshes along the coast, North Carolina to Florida and Texas. Summer and fall. 



12. VINCETOXICUM Walt. 

 Twining perennial vines or low shrubby plants, mostly pubescent. Leaves opposite : 

 blades commonly heart-shaped. Inflorescence axillary, peduncled or sessile. Flowers soli- 

 tary or few in small clusters, or more commonly in loosely-flowered umbel-like cymes. Calyx- 

 lobes oblong or lanceolate, acute or acuminate, commonly with 1-2 glands in each sinus. 

 Corolla variously colored or white, rotate : lobes 5, dextrorsely convolute in bud. Crown 

 annular, saucer-shaped or cup-shaped, single or double, the outer sometimes surrounded by 

 a fleshy ring or fold, simulating a third ring, often annular and cohering with the base of 

 the corolla, entire, crested or appendaged within, sometimes connected with the gynostegium 

 by 5 fleshy ribs. Gynostegium arising from the base of the corolla, sessile or raised on a 

 column. Anthers usually with a short narrow, if any, scarious tip, borne on the margin 

 of or close under the disk of the stigma, often doi'sally appendaged by a short corneous 

 projection ; sacs opening more or less transversely and outwardly, or from above. PoUinia 

 horizontal, sometimes pointing inwards. Stigma depressed, sometimes barely conic in the 

 center, sharply 5-angled, usually with radiating raised margins. Follicles thiclj, taper- 

 ing, glabrous, muricate or warty, or 3-5-costate-angled. [Gonolohus Michx. in part.] 



A. Stems twining : vines with large leaves. 



PoUinia pyriform on broad angled caudicles : crown a low, fleshy entire or 10-undulate ring : anthers 

 with a narrow dorsal projection. 

 Corolla green-reticulate : crown entire : stigma raised on a slender 5-angled column : follicles 

 muricate. 

 Column slender, unappendaged : corolla 1.4 cm. broad. 1. V. rcticulatum. 



Column stout, appendaged at the base by 5 erect horn-like projections : 



corolla 2 cm. broad. 2. V. Alahaviense. 



Corolla not reticulate : crown 10-undulate, unappendaged within : follicles 

 4-.>angled or costate or winged. 

 Leaf-blades oblong-ovate or oblong-oval, thickish, abruptly acuminate 



at the apex. " 3. T'. snberosiim. 



Leaf-blades broadly ovate or sometimes oblong-ovate, thin. 4. V. (jonocarpo^. 



PoUinia oblong on slender twisted caudicles : crown low, lO-crenate, with 

 5 crenations broader, obscurely crested within, the 5 alternate divisions 

 truncate or bifid at the apex : follicles muricate. 

 a. Corolla dull reddish or greenish purple, some of them turning yellowish.' 

 Corolla greeni.sh purple. 



Alternate longer divisions of the crown truncate and bifid, thinner than the rounded, broader, 

 obscurely crested divisions. 



