Invasive Species: Humulus japonicus, Japanese Hop
Japanese hop is an invasive annual, climbing or trailing vine that is native to eastern Asia. This vine has five-lobed leaves (generally), downward pointing prickles on the stem and bracts at the base of the petioles. Leaves are opposite, rough, 2 to 5 in. (5 to 13 cm) long, five- to nine-lobed with toothed margins. Most leaves will have five lobes, but the upper leaves may only have three. 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 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.
What are invasive species and why should we be concerned about them?
Taxonomy: Scientific and Common Names for This Species
Urticales > Cannabaceae > Humulus japonicus Sieb. & Zucc
Synonym(s): none
Humulus japonicus – USDA PLANTS Profile
Distribution Maps
Japanese hop – The reported distribution of this invasive species across the United States. (Source: Invasive Plant Atlas of the United States)
Up-to-the-minute distribution maps and why they are important.
Reporting This Invasive Species
What is the best way and place to report the occurrence of an invasive species?
How to report an invasive species sighting to EDDMapS – Early Detection & Distribution Mapping System
EDDMapS – Report an invasive species to EDDMapS
Cooperative Extension Offices – Find your local Cooperative Extension office on this map provided by USDA
How to Identify
This invasive species can be identified by looking for the characteristics described in the paragraphs that follow.
Vine
An invasive annual, climbing or trailing vine that is native to eastern Asia.
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| John M. Randall, The Nature Conservancy, bugwood.org | Leslie J. Mehrhoff, University of Connecticut, bugwood.org |
Foliage
This vine has five-lobed leaves (generally), downward pointing prickles on the stem and bracts at the base of the petioles. Leaves are opposite, rough, 2 to 5 in. (5 to 13 cm) long, five- to nine-lobed with toothed margins. Most leaves will have five lobes, but the upper leaves may only have three.
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Foliage |
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| Chris Evans, River to River CWMA bugwood.org | Chris Evans, Illinois Wildlife Action Plan, bugwood.org |
Flower
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.
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| Leslie J. Mehrhoff, University of Connecticut, bugwood.org | Leslie J. Mehrhoff, University of Connecticut, bugwood.org |
Fruit
Fruit is an achene.
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| Leslie J. Mehrhoff, University of Connecticut, bugwood.org | Carole Ritchie, USDA NRCS PLANTS Database, bugwood.org |
Native Species That Resemble Japanese Hop
Humulus lupulus, common hop – Images at invasive.org
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| Karan A. Rawlins, University of Georgia, bugwood.org | Robert Vidéki, Doronicum Kft., bugwood.org |
– Images at invasive.org
| bugwood.org | bugwood.org |
Additional Images for Japanese Hop
Japanese hop – Images at Invasive.org
Learning Resources for Japanese Hop
Weeds Gone Wild Fact Sheet – Plant Conservation Alliance, Alien Plant Working Group
Additional Information, Biology, Control and Management Resources
Control and management recommendations vary according to individual circumstances. Location, habitat, weather, and a variety of other conditions are factors that help determine the best treatment choice. To find the safest and most effective treatment for your situation, consult your state’s land-grant institution. If you will use chemicals as part of the control process, always refer to the product label.
United States Land-Grant University System – Find your land-grant university’s College of Agriculture, Cooperative Extension Service, or other related partner on this map provided by USDA.
Fact Sheet – Pennsylvania Dept. of Conservation and Natural Resources
Weed of the Week – USDA Forest Service
Element Stewardship Abstract – The Nature Conservancy
Weed Identification Guide – Virginia Tech