Thladiantha dubia (Red Hailstone): Minnesota Wildflowers

Thladiantha dubia (Red Hailstone)

Plant Info
Also known as:	Golden Creeper, Manchu Tubergourd
Genus:	Thladiantha
Family:	Cucurbitaceae (Cucumber)
Life cycle:	perennial
Origin:	Asia
Status:	Invasive - ERADICATE!
Habitat:	part shade, shade, sun; moist soil; stream and river banks, thickets, fields, roadsides, waste places, gardens
Bloom season:	June - September
Plant height:	6 to 20-foot vine
Wetland Indicator Status:	none
MN county distribution (click map to enlarge):
National distribution (click map to enlarge):

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Detailed Information

Flower:

One to a few stalked flowers arising from leaf axils all along the stem, with separate male and female flowers on different plants (dioecious). All flowers are about 1 inch long, yellow, bell-shaped with 5 recurved lobes. Male flowers have 5 short yellow stamens inside the tube; female flowers have a 3-parted style with disc-shaped stigma. The calyx surrounding the flower has 5 oblong, recurved lobes, is light green and covered in long, white hairs on the outer surface. Flower stalks are covered in a mix of long straight and short hooked hairs.

Leaves and stems:

Leaves are alternate, heart-shaped, 2 to 6 inches long, 1½ to 4 inches wide, minutely toothed around the edge, on a stalk up to 2½ inches long.

Opposite a leaf is a long, unbranched, hairy tendril that winds around other vegetation to help the vine climb. Stems are light green and weakly angled. Leaves, stalks and stems are all covered in a mix of long straight and short hooked hairs, the hooked hairs sticking like Velcro™ to anything and everything, even skin.

Fruit:

Fruit is berry-like, oval-elliptic, up to 2 inches long, with a hairy, green to red rind around fleshy pulp containing numerous gray to black seeds.

Plants also reproduce by below ground tubers, similar to small potatoes.

Notes:

This invasive species is new to Minnesota, first recorded in Stillwater in 2013 (the Cass County report shown on the national map cannot be confirmed). At the time little was known about the species; reports are that it was treated and thought to be eradicated. They were wrong. It silently multiplied over 5 years and became a massive infestation, not unlike kudzu, covering much of the ground and climbing 20 feet or more into the trees, smothering everything. Reports that it is hardy only to zone 6 and is shade intolerant are obviously incorrect, since the site where we photographed it is zone 4 in a fairly shady ravine.

The population in Stillwater is entirely male, which seems to be the norm in North American infestations. While an all-male or all-female population won't produce above-ground fruit, they can spread far and wide by below-ground tubers connected by rhizomes. One report notes new tubers can be produced every 4 to 8 cm (1½ to 3 inches). I followed the trail from one tuber to another and measured close to 2 feet, but that was only one specimen. Tubers could have been much more abundant in other parts of the population. A report from Canada noted their attempts at chemically treating it failed and the most reliable control method was likely digging up all the tubers.

If you see this thing in the wild, get rid of it while you can. At minimum, tell someone!

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in Stillwater. Female flower, fruit, tubers by Rob Hille, via Wikimedia Commons, used under CC BY-SA 4.0

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Eric
on: 2018-10-03 10:39:31

Is this supposed to say Carver County? (the Cass County report shown on the national map cannot be confirmed) Also, what's the deal with the Sherburne County point?

Posted by: K. Chayka
on: 2018-10-03 12:26:33

Eric, check EDDMapS for info on the Carver and Sherburne county points. I confirmed them myself. There is another point from Otter Tail County that was reported last year and just recently verified, which should be added to our Minnesota map. The Cass County report on the national map is from 1963 and probably no longer exists.

Posted by: Tony - Washington County
on: 2019-03-29 16:44:41

Washington County Conservation District staff are currently working up management approaches to two populations in Stillwater. Initial WCD trials using glyphosate and triclpyr show promise, with foliar applications resulting in complete rot of underground tubers. WCD will assess in Spring and throughout the summer of 2019 to assess effectiveness of these and ongoing treatments. The Canadian study (uncited in the Minnesota Wildflowers website) is likely a trial of Callisto and atrazine. Similar studies using these as well as 2 4 dinitrophenol have had little success.

A German study from 1984 suggested success with glyphosate.

WCD performed manual removal in an area within one of the infestation zones in 2018 and identified a number of problems with mechanical removal at scale. Issues with hand removal approach on large infestations include the following problems: weak stems breaking easily leaving rhizomes in-tact, mass amounts of biomass removal, potential for creating new infestations with large amounts of now liberated stems and roots, and exposure of large areas of bare soils as a result from digging out hundreds of tubers per 10 x 10 section.

Based on published information thus far, it is not clear that herbicide treatment is ineffective. WCD plans to use an adaptive approach to controlling known infestations and provide information to the public regarding effectiveness of different controls.

Posted by: Alan Branhagen - Carver
on: 2019-08-07 21:39:10

Growing along the bike trail between the Casey's and Riverside Park: photographed August 7,2019

Posted by: John Hengel - St. Cloud
on: 2020-07-23 10:01:39

Have at my park.

Posted by: K. Chayka
on: 2020-07-23 14:21:39

John, this needs to be eradicated ASAP. Please contact the city or county agency that owns the park and refer them to Washington County Conservation District for info on control methods.

Posted by: Janet Van Sloun
on: 2022-10-26 18:31:25

Today at the Upper Midwest Invasive Species Conference, Mark Renz of U of WI, Madison presented his herbicide research on Thladiantha dubia: fall is best timing for foliar spray using Remedy (triclopyr) or Escort (metsulfuron); will take more than two years to get under control. Under-reported; early detection is critical. Hot-spot in SW Wisconsin.

Posted by: John - Houston County
on: 2023-07-06 17:16:20

Don't get mad at me but I think I might've been the one who introduced it to Minnesota. I have a mix of Male & Female Plants growing on my Property but They have no Pollinators here, so I have to Hand Pollinate them in order to get fruit. Have you tried eating the Ripe fruits? They Taste delicious but have heat in the raw state. I've eaten lots of them cooked, Very delicious, Sweet & aromatic. I've always eaten the fruit but read that the tubers and the Leaves are somehow edible? Have you tried them? Are they edible raw or cooked? Cuz if so, That might be the solution honestly.

Posted by: K Chayka
on: 2023-07-07 14:34:07

John, foraging/harvesting is not an effective way to eradicate this from natural areas. Like garlic mustard and other invasive weeds, foragers never take it all so any left on site will continue to propagate.

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