Japanese hop USDA PLANTS Symbol: HUJA
U.S. Nativity: Exotic
Habit: Vines
Humulus japonicus Siebold & Zucc.

Jump to: Resources | Images | Distribution Maps | Sources
Taxonomic Rank: Magnoliopsida: Urticales: Cannabaceae
Native Range: Temp. Asia - China, Japan, & Russ. Fed (GRIN);

Appearance
Humulus japonicus 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.
Foliage
Leaves are opposite, rough, 2-5 in. (5-13 cm) long, 5-9 lobed with toothed margins. Most leaves will have five lobes, but the upper leaves may only have three.
Flowers
Flowers originate in the leaf axils and are green with five 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
Fruit is a yellow-brown ovoid achene. The small seeds are distributed by wind and water.
Ecological Threat
These vines can grow to 35 ft. (10.7 m) in one growing season, allowing them to infest large areas crowding and out competing native vegetation. Humulus japonicus was introduced into North America in the mid-to-late 1800s as an ornamental.

Identification, Biology, Control and Management Resources

Selected Images from Invasive.orgView All Images at Invasive.org


Infestation;
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Foliage;
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Foliage;
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Feature(s); The down-curved bracts and sharp prickles help to identify this plant
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Foliage; Leaves and Inflorescences
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Foliage;
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Infestation;
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Seed(s);
Carole Ritchie, USDA NRCS PLANTS Database, Bugwood.org
Additional Resolutions & Image Usage

EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org
 


State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.

U.S. National Parks where reported invasive:
Chesapeake and Ohio Canal National Historical Park (Maryland, Washington, D.C., and West Virginia)
Colonial National Historical Park (Virginia)
George Washington Memorial Parkway (Virginia)
Monocacy National Battlefield Park (Maryland)
Rock Creek National Park (Washington, D.C.)



Invasive Listing Sources:
Connecticut Invasive Plant Working Group
Delaware Natural Resources and Environmental Control, 2004
Indiana Native Plant and Wildflower Society
Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Mid-Atlantic Exotic Pest Plant Council, 2005
Virginia Invasive Plant Species List