Red Hailstone (Thladiantha dubia)
Other common names: Manchu tubergourd, Golden creeper, wild potato
Family: Cucurbitaceae
Life form: herbaceous perennial climbing vine
History & Introduction
Native to Russia, Northern China and Korea, red hailstone was likely introduced to North America as an ornamental plant or vegetable crop. It has been identified in Illinois, Massachusetts, Minnesota, New Hampshire, [upstate] New York, and Wisconsin in the United States as well as in Manitoba, Ontario, and Quebec provinces in Canada. It was also recently reported in one location in Connecticut in 2021.
Identification & Biology
It can grow in a variety of habitats, from disturbed edges and agricultural fields to forested floodplains. It can also withstand various light conditions from full sun to shade.
- Habit: Herbaceous perennial climbing vine
- Leaves: Alternate, simple, and heart-shaped with irregularly toothed edges.
- Stem: Light green and weakly angled with a variety of long straight and short hooked hairs, the latter sticking to clothes and animals very easily. Along the stem there are curling tendrils, found opposite to each leaf, which help it to climb and spread.
- Flowers: Dioecious, with conspicuous bell-shaped yellow or golden flowers with five petals fused at the base producing a tube. Flower stalks are hairless.
- Fruits: Small (up to 2” long) red cucumber-like fruits with vertical stripes.
- Roots: Spreads through rhizomes that produce root tubers that can sprout new plants.
- Phenology: Flowering July through September.
Lookalikes:
- Wild yam (Dioscorea villosa) — native. You can differentiate it from its small stalkless green-white flowers and heart-shaped leaves. Wild yam leaves also have deep veins radiating from the base and fruit that is a 1” and broadly-winged three-section fruit with two seeds inside.
- Common garden squashes and melons, as well as morning glory.
Damage & Concern
While the vines die back each winter, they can grow very quickly, as much as 18 feet during the growing season. They rapidly shade out native plants the same way other invasive vines do (eg: english ivy, kudzu), which can reduce native biodiversity. Where it has been introduced in states like Wisconsin and Minnesota, the plants that have been reported have all been male, so spread via seed is not presently a large concern. However, the root tubers are buoyant and can easily break off from the plant and spread through waterways. The tubers may be persistent which makes eradication difficult once it is established.
In Wisconsin it is considered a regulated species. In several other states where it has been reported, it is a high priority invasive where rapid response is recommended.
Management
Currently, there are no known reports of red hailstone within LIIMSA, however in November 2021 a small infestation in Kent, CT was reported by the Connecticut Agricultural Experiment Station. In 2017 it was reported in St. Lawrence county NY; however it has not recently been mapped or tiered within NYS. Utilizing tools such as iMapInvasives and iNaturalist are vital to understanding its extent within the region so that we may employ early detection and rapid response to prevent its introduction and spread. You can also contact LIISMA directly if you think you’ve seen this species: invasive@liisma.org.
An anecdotal report from Canada has described chemical control as unsuccessful, and instead repeated digging of tubers was the course of action taken.
