Humulus japonicus Siebold & Zucc.

Japanese hop is an annual, climbing or trailing vine that is native to eastern Asia. This vine has 5-lobed leaves (generally), downward pointing prickles on the stem and bracts at the base of the petioles. Leaves are opposite, rough, 2-5 in. (5-13 cm) long, 5-9 lobed with toothed margins. Most leaves will have 5 lobes, but the upper leaves may only have 3. Flowers originate in the leaf axils and are green with 5 petals. Male and female flowers occur on separate plants (dioecious). Female flowers occur in cone-shaped clusters that hang down and the male flowers occur in upright flower stems. Fruit is an achene. Japanese hop was introduced into North America in the mid-to-late 1800s as an ornamental. These vines can grow to 35 ft. (10.7 m) in one growing season.

Identification, Biology, Control and Management Resources