Thladiantha dubia (Red Hailstone)
|Also known as:||Golden Creeper, Manchu Tubergourd|
|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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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:
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.
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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- Thladiantha dubia plant
- Thladiantha dubia plants
- Thladiantha dubia plants
- climbing Thladiantha dubia
- sprawling Thladiantha dubia
- close-up of long straight and short hooked hairs
- tubers are starchy like potatoes
- tubers float and may spread down waterways
- tubers are connected by underground stems (rhizomes)
- tubers can be as close as 1½ inches apart, ©Rob Hille
- female flower ©Rob Hille
- male flower
Have you seen this plant in Minnesota, or have any other comments about it?