Japanese Hops Humulus scandens

Japanese Hops is an annual with a tap root, a climbing or twining vine in the hemp family. It is native to eastern Asia, from Russia to North Vietnam. The plant is often found escaped from cultivation along rivers and stream, abandoned home sites, and other moist, disturbed habitats. The plant's stems are twining with branched stalk hairs that aid it in climbing. These stems can reach up to 35 feet and allow the plant to climb structures or to spread along the ground. The leaves are opposite, mostly 5-lobed with a rough texture. Flowers are greenish, appearing in mid-summer to fall. There are separate male and female vines. Both produce small, five-petaled flowers. Male flowers occur in airy clusters, while female flowers are in short spikes. Fruits appear in elongated clusters, enclosed in a papery sac-like bract. Japanese Hops is a larval food source for several species of butterflies. The genus name comes from a Latinized Medieval name of the hop plant. The species epithet, scandens, means "climbing."

Although it can grow in just about any soil type, its most vigorous growth will be in moist fertile loam.  

Although an annual, Japanese Hops can survive mild winters. This drought-tolerant plant is listed as invasive in several of the United States and has escaped cultivation in many areas where it may displace desirable species. In the United States, most infestations are in eastern states, but the species is spreading in the Midwest. Seeds are spread by wind and water, allowing the plant to reseed itself and often forms dense colonies of overlapping vines. For this reason, planting Japanese Hop is not recommended. Japanese Hops can easily be distinguished from the better behaved American Hops; Japanese Hops have leaves with 5–7 lobes, American Hops have leaves with 3 lobes or none.

This plant serves as a host plant for the Gray hairstreak (Satyrium sylvinus), Eastern comma (polygonia comma), Question mark (plygonia interrogationis), and Red Admiral (Vanessa atalanta) butterflies. 

Diseases, Insect Pests, and Other Plant Problems:

The plant is invasive in some states. Control can be maintained by pulling plants before its seeds set, ensuring to remove as much of the root system as possible.  No known diseases or insect problems.