1. Parthenocissus tricuspidata (Siebold & Zuccarini) Planchon in A. L. P. P. de Candolle and C. de Candolle, Monogr. Phan. 5: 452. 1887.
Boston or Japanese ivy, vigne vierge tricuspidée Boston or Japanese ivy, vigne vierge tricuspidée
Ampelopsis tricuspidata Siebold & Zuccarini, Abh. Math.-Phys. Cl. Königl. Wiss. 4(2): 196. 1845
Lianas, high climbing. Tendrils 5–10-branched, with adhesive discs. Leaves usually simple, sometimes palmately compound on older plants; petiole usually longer than, sometimes ± equaling, blade; blade lustrous adaxially, ovate to cordate-ovate or cordate-orbiculate, 4.5–17 × 4–16 cm, 3-lobed or leaflets 3, thin, herbaceous, base truncate to slightly cordate, margins crenate to crenate-serrate, apex acute to short-acuminate, surfaces glabrous or abaxial veins puberulent. Inflorescences ± divergently branching, without distinct central axis. Flowers yellowish green. Berries globose, 5–8 mm diam. 2n = 40.
Flowering Jun–Jul; fruiting Sep–Oct. Thickets, forest edges, disturbed places; 50–500 m; introduced; Ont.; Conn., D.C., Ill., Ind., Iowa, Ky., Maine, Mass., Mo., Nebr., N.J., N.Y., N.C., Ohio, Pa., S.C., Tenn.; e Asia.
Parthenocissus tricuspidata has escaped from cultivation and become locally naturalized throughout much of eastern North America.