Herbs. Stems annual, immature erect, older climbing, 1-2 m, occasionally branching, herbaceous, glabrous; prickles absent. Leaves numerous, evenly distributed; tendrils numerous, long, functional; blade deltate-ovate, pandurate, or cordate-ovate, the larger hastate, thin, 5-12 × 2-5 cm, coriaceous, glabrous, glaucous abaxially, base truncate to subcordate; apex round to cuspidate. Umbels solitary or in sets of 3, axillary to leaves, 10-35-flowered, loose, subglobose; peduncle shorter than to 1.5 as long as subtending leaf. Flowers: perianth greenish; tepals 1.5-2.5 mm; anthers equaling or slightly larger than filaments; ovules (1-)2 per locule; pedicel 0.3-1.5 cm. Berries blue to black, subglobose, 4-6 mm, glaucous. 2n = 30. Flowering May--Jul. Bogs, wet woods, marshes, pocosins; Del., D.C., Ga., Md., N.J., N.Y., N.C., Pa., S.C., Va.
Herbaceous, unarmed, climbing to 2 m, occasionally branched; lvs numerous, mostly with tendrils, the blade 5-12 cm, thin, glabrous, the larger ones hastate, with concave margins, truncate to subcordate at base, rounded and cuspidate at the tip; peduncles axillary to foliage- lvs, often 2 or 3 from the same axil, terete even at maturity surpassing the petiole and often nearly equaling the blade, with 10-30 fls; tep 1.5-2.5 mm; anthers 0.5-1 mm; fr black, glaucous, 4-6 mm, with 1-3 seeds; 2n=30. Moist or wet low places on the coastal plain; N.J. and Del. to Ga. May. (S. tamnifolia)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.