Japanese Hops (Humulus japonicus)

Japanese hops is a climbing, annual vine that grows rapidly, up to 8 feet. Leaves are opposite, 2 to 5 inches long, serrated on the edges and palmately divided, usually into 5 or more lobes (though upper leaves can be 3-5 lobed). Petioles (leaf stems) tend to be as long or longer than the length of leaves. Stems and leaves have rough hooked climbing hairs to grasp and twine clockwise up nearby vegetation. Male and female flowers are on separate plants and bloom from mid to late summer. Bracts on the pistillate (female) spikes have small, spiny hairs.

The native hops (Humulus lupulus -- several varieties) is found throughout the state. A non-native variety grown for beer-making has been reported growing wild in three counties. All H. lupulus varieties typically have 3-lobed leaves (though upper leaves sometimes lack lobes), with petioles shorter than leaf-length.

In Wisconsin, Japanese hops has been found in southern and western counties. It reproduces by seeds dispersed by wind and water. Preferring moist soils, it can form dense stands in floodplains and along streambanks and lakeshores, but can thrive in disturbed areas such as roadsides and urban lots. It can be found in full sun or shade.

Plants can be hand-pulled and removed from the area before seeds ripen. The herbicide glyphosate can be used on foliage before plants flower.

Photo from Virginia Tech Weed ID Guide [exit DNR]	Photo by David Eagan, WDNR
Petiole longer than leaf; photo from Virginia Tech Weed ID Guide [exit DNR]	Leaves typically 5-7 lobed; photo by John Randall, TNC
Photo by John Randall, TNC	Showing its climbing nature; photo by D. Eagan, WDNR
Photo by David Eagan, WDNR

UW Herbarium
USDA

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