Vines climbing, usually unarmed. Stem branched, terete, to 10 m, woody. Petiole 1.5--5 cm, narrowly winged for 1/3--1/2 its length; abscission zone distal; tendrils usually present. Leaf blade sometimes turning blackish when dried, ovate to elliptic, (5--)10--20 × 3--12 cm, papery or subleathery, adaxially slightly shiny, base rounded or truncate, apex submucronate. Inflorescence of (1 or)2 or 3 umbels, 3--6(--10) cm, basally prophyllate; umbels of both sexes 6--20-flowered, base slightly thickened. Male flowers: tepals greenish yellow, 6--7 × 0.6--1.5 mm. Female flowers unknown (in China). Berries dark red, globose, 1.5--2 cm in diam. Fl. Oct--Dec, fr. May--Jun.

Chinese records of Smilax macrocarpa Blume (e.g., in FRPS) are referable to S. megacarpa.

Forests, thickets, shaded slopes; near sea level to 1500 m. Guangxi, Hainan, S Yunnan [Cambodia, India, Laos, Malaysia, Myanmar, Philippines, Thailand, Vietnam].