Japanese hops is native to temperate regions of eastern Asia—China, Japan, Korea, Taiwan and the
Russian Federation—as well as to tropical Vietnam. It was probably imported for cultivation,
but it escaped and spread quickly. It is related to the
variety of hops, Humulus lupulus, used for flavoring and preserving beer, and may be
used as a less suitable substitute for this purpose. Japanese hops
is considered an invasive in Connecticut, Delaware, Indiana, Maryland, Pennsylvania, Virginia, and the District of Columbia.
Identification: This fast-growing vine has tiny hooks on its stems
and leaves that allow it purchase on nearly anything it encounters, reaching between 3-20′ (91-609 cm) in length.
If you want to get technical, Japanese hops are bines, not vines: they climb with little hooks
rather than wrapping tendrils around things like grapes, or using suckers like ivy.
Stems are green or reddish purple, with ridges running along the length of the stem.
Leaves are rough, with short hairs and 5-9 palmate lobes, and are
2-6″ (5-15 cm) in size, with long petioles (stems). Plants are dioecious. Male plants have
large cone-shaped
panicles up to 10″ (25 cm) long and 5″ (12 cm) wide;
female flowers are about 1″ (2.5 cm) long. Though the panicles are large, the flowers are pale and unremarkable, each
about ⅛″ (3.2 mm) in size. They appear early to mid-summer.