Humulus japonicus, Japanese Hop

Gardens & Landscapes, Invasive Species, Extension Master Gardener January 28, 2013 Print Friendly and PDF

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.

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.

Chris Evans, River to River CWMA, Bugwood.org

Foliage

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.

Leslie J. Mehrhoff, University of Connecticut, bugwood.org Leslie J. Mehrhoff, University of Connecticut, bugwood.org

Fruit

Fruit is an achene.

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

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


 

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.