Herbs , annual, vining, 0.5-2.5 m. Stems usually branched. Leaves: petioles usually longer than blades. Leaf blade cordate, palmately 5-9-lobed, 5-12 cm, margins of lobes serrulate, apex acuminate; surfaces abaxially with veins pubescent, with stiff hairs, glands yellow, sessile, discoid, adaxially margins of younger leaf blades with stiff cystolithic hairs. Inflorescences: staminate inflorescences erect, 15-25 cm, flower anthers without glands; pistillate inflorescences spikes, conelike, ovoid; bracteole ovate-orbiculate, 7-10 mm, pilose, margins densely ciliate-hairy. Infructescences pendulous, green, conelike, ovoid to oblong, (1-)1.5-3(-4) cm; bracteoles without yellow glands. Achenes yellow-brown, ovoid-orbicular, inflated to lenticular, 4-5 mm, glandless. 2 n = 20, including 6 chromosomes concerned with sex determination.
"Weedy annual vine; stem and lvs much rougher than in no. 1 [Humulus lupulus L.]; petioles commonly longer than the 5–9-lobed blades; uppermost lvs usually 3–5-lobed; mature pistillate spikes to 2 cm, their bracts relatively small, under 1 cm, densely spinulose-ciliate, dull green, conspicuously and abruptly acuminate, scarcely glandular, releasing the ripe achenes; 2n=32 (pistillate), 34 (staminate). Native of e. Asia, escaped from cult. from N. Engl. to N.C. and Mo. July–Oct."
|Japanese hop(s), houblon japonais|