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Latex clear. Stems puberulent in single line; dwarf axil­lary branches common (pseudo­stipules). Leaves: 1–3 early-caducous stipular colleters on each side of petiole; petiole 1–9 cm, puberulent in single line to glabrate; blade pinnipalmately veined, ovate or deltate, 2–11 × 1.5–10 cm, chartaceous, base shallowly to deeply cordate or sagittate, with 3–8 laminar colleters, margins puberulent-ciliate or glabrate, apex acute, attenuate, acuminate, or apiculate, surfaces minutely puberulent to glabrate on veins. Inflorescences racemiform to paniculiform, solitary (paired) at nodes, 6–30-flowered; peduncle 0.2–2(–6.5) cm, puberulent in single line; bracts caducous, 1, at base of each pedicel. Pedicels 3–12 mm, tomentulose. Flowers: calyx lobes erect, lanceolate to ovate, 1.5–2 mm, apex obtuse, acute, or acuminate, puberulent to glabrate, margins ciliate to glabrate; corolla cream, campanulate, tube 1–1.5 mm, lobes erect to spreading, plane to somewhat twisted, linear-lanceolate, 3.5–6 mm, glabrous, inframarginal adaxial ridges absent; corona united to column near base, composed of 5 distinct segments, cream, laminar, slightly exserted from corolla, ovate with apex deeply divided into 2 subulate, usually twisted lobes, 4–6 mm; style apex conic. Follicles ovoid to lance-ovoid, straight to falcate, 7–15 × 2–3.5 cm, apex attenuate, thick-walled. Seeds 50–100, tan to light brown, 8–10 × 5–7 mm, thickly winged, chalazal margin erose, faces minutely foveolate; coma white to tawny, 3–4 cm. 2n = 22.

Phenology: Flowering Apr–Nov; fruiting Jul–Dec.
Habitat: Streamsides, flood plains, canyons, dunes, roadsides, fields, gardens, cities and towns, especially on fences, riparian woods, thickets, deciduous forest, prairies.
Elevation: 0–700 m.

Distribution

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Ala., Ark., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mich., Minn., Miss., Mo., Nebr., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va.

Discussion

Cynanchum laeve is a common and fairly weedy spe­cies from valleys west of the Appalachians to the central Great Plains. It is especially common in valleys of trib­utaries to the Mississippi River. It is far more evident as a weed on fences along roads, in fields, and in urban lots and gardens than in less-disturbed vegetation. Prior to mas­sive anthropogenic environmental change in North America, the natural habitat was likely riparian vegetation. The deeply seated rhizomes are difficult to remove, and the vine is hard to eradicate from managed landscapes, where they are not necessarily unwelcome guests. The flowers are sweetly fragrant, hence the com­mon name honeyvine. Cynanchum laeve has been reported from Ontario, but the author has not seen spec­imens to confirm its presence in the province. A report from Idaho is based on a misidentified specimen of Metaplexis japonica (Thunberg) Makino. Occurrences on the western and northern margins of the range and east of the Appalachians likely represent recent range expansion.

Selected References

None.

Lower Taxa

None.