Perennial herb 1.5-2 m tall, andromonoecious. Lower part of stem with stiff hairs. Rhizomes stout and horizontal. Leaves 60-100 cm long and wide, tripinnately to bipinnately ternate, stipulate; stipules 2-2.3 cm long, 0.7-1 cm wide, narrowly triangular, often becoming leaf-like and enlarged, especially for those on the lower part of the stem; upper leaves pinnate to bipinnate or trifoliolate; petioles 12-22 cm long, pubescent with soft and scabrous hairs; leaflets 5.5-22 cm long, 4-10.5 cm wide, papery, basal leaflets ovate, other leaflets ovate to narrowly so, acuminate to acute at apex, cordate, subcordate to rounded at base, often oblique on lateral leaflets, serrate to serrulate at margin; lateral veins 8-10 on each side, conspicuous on both surfaces, sparsely scabrous on adaxial surface, pilose along veins and veinlets on abaxial surface, petiolules 0-2 cm long, pilose. Inflorescence 30-65 cm long, a terminal panicle with the lower 2-5 primary branches subtended by leaves rather than bracts, pilose, consisting of 20-50 primary branches, mostly racemosely or sometimes panicunately arranged on a main axis, often 2-8 forming a circle on the upper half of the main inflorescence axis, each primary branch 3-22 cm long, consisting of 1-10 umbels; terminal umbels mostly 35-95-flowered, pedicels 9-14 mm long, pubescent, tip of pedicels enlarged and with a cluster of scabrous hairs; lateral umbels 18-35-flowered, pedicels 7-9 mm long; bracts of primary branches 4-9 mm long, 0.6-0.8 mm wide, linear, pilose; bracteoles 1.6-2 mm long, 0.1-0.2 mm wide, linear, pilose. Sepals 0.3-0.4 mm long, 0.2-0.3 mm wide, narrowly triangular. Petals 1.5-1.8 mm long, 0.9-1 mm wide, ovate, with a conspicuous vascular bundle in the middle. Stamens 5, 2.2-2.3 mm long, filaments 1.7-2 mm long, anthers 0.7-0.8 mm long, 0.4-0.5 mm wide, ovate. Ovary 5-locular, styles 0.6-0.8 mm long at anthesis, base of ovary slightly pilose with a few scattered hairs, the top part of the ovary conspicuously exposed and appearing like a stylopodium. Fruits 3.2-3.5 mm long and wide, globose, persistent styles 5-divided, connate at the base.