Dioscorea villosa (Wild Yam)

Plant Info
Also known as: Yam-root, Colic Root
Genus:Dioscorea
Family:Dioscoreaceae (Yam)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; moist to dry, sandy to rocky soil; woods, thickets, fencerows, shorelines, bluffs, railroads
Bloom season:June - July
Plant height:6 to 15 feet
Wetland Indicator Status:GP: FAC MW: FAC NCNE: FAC
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 6-petals Cluster type: panicle Cluster type: raceme

[photo of male flowers] Dangling clusters of nearly stalkless flowers arising from the leaf axils, with male and female flowers on separate plants. Flowers of both are about 1/8 inch across, yellowish to greenish white, saucer-shaped with 6 tepals (petals and similar sepals). Male clusters are 1 to 12 inches long, usually forked or branched, the flowers with 6 short, yellow stamens and strung along the cluster stalk in groups of 1 to 3.

[photo of female flowers] Female clusters are 1 to 8 inches long and unbranched, the flowers single and spaced ¼ to ½ inch apart, each flower sitting at the tip of an ovary about 1/3 inch long with 3 broad wings.

Leaves and stems: Leaf attachment: alternate Leaf attachment: whorl Leaf type: simple

[photo of leaves] Leaves are mostly alternate, though may be whorled or nearly so near the base of the plant, 1 to 5 inches long, ¾ to 5 inches wide, heart-shaped, sharply pointed at the tip, with 7 to 11 deep veins radiating from the base and a hairless stalk up to 6 inches long that may be ridged or narrowly winged, sometimes with a few hairs where the stalk joins the blade. Leaf edges are toothless and sometimes a bit wavy. The upper surface hairless and the lower variously hairy, sometimes hairless or glandular. Color is light to medium green. Stems are little branched, leafy, grooved or narrowly winged, mostly hairless, lack tendrils and twine around other vegetation for support, and spreads by seed or branching rhizomes.

Fruit: Fruit type: capsule/pod

[photo of fruit] The ovary expands to about 1 inch long as fruit develops, forming a broadly-winged, 3-sectioned capsule, each section containing 2 seeds, sometimes only 1. The capsule ripens from green to brown in fall.

Notes:

Wild Yam is a pretty vine; while the dangling flower clusters aren't particularly showy, the heart-shaped leaves are interesting and the fruit distinctive, and distinguish it from other vining plants in Minnesota. There is considerable variation in leaf size, degree of hairiness, leaf arrangement near the base of the stem, capsule and seed size and shape, and stem characteristics; some attempts have been made to separate the species into distinct varieties but they have not held up. Wild Yam has long been used medicinally to treat a wide variety of conditions and ailments, though at least one study shows it may cause kidney damage. Buyer beware.

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More photos

Photos by K. Chayka taken at Wild River State Park, Chisago County. Photos courtesy Peter M. Dziuk taken at Falls Creek SNA and William O'Brien State Park, Washington County.

Comments

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

Posted by: Elizabeth T - Carroll's Woods Park, Rosemount Mn
on: 2017-08-12 20:49:04

Delighted to find this in Carroll's Woods and also in woods just north of Mt. Olivet Retreat Center (nw of Castle Rock)

Posted by: Pat Espeset - Rochester
on: 2019-06-11 10:19:04

We have a wooded hillside behind our church which we've worked on diligently to remove buckthorn. We've made significant progress on that front.

We'd noticed this unique little vine a couple years ago along the edge of the woods, which we ID'ed as wild yam. Now that the woods are cleared of much of the buckthorn and open to a lot more light, the wild yam has moved aggressively from the edge of the woods into the wooded hillside. It's sending up shoots everywhere and covering anything it can grab on to, including the other natives that we've been delighted to discover in our woods.

I haven't come across an article about how invasive it is. But in our situation it is out of control and more concerning to me than the buckthorn was. Are we the only ones who see it as invasive?

Posted by: K. Chayka
on: 2019-06-12 07:43:19

Pat, are you certain it's wild yam and not some other vine? I'm not aware of any reports that it is overly aggressive, though many native vines can be that way in cultivation.

Posted by: Bill Carter - Rochester
on: 2019-07-30 11:56:28

I visited the Rochester church site that Pat posted about earlier. It is indeed Dioscorea villosa and in some areas it's completely covering the ground. Buckthorn had choked out smaller trees so with those gone there is no where for the vine to go. Pat has offered to let me harvest the seed and I will also remove some roots for transplanting elsewhere. I believe this is just a temporary problem and other plants will fill in. Cheers to Pat and the church for working to restore this area!

Posted by: Mike Kraemer - Burnsville - Alimagnet Park
on: 2019-09-25 22:53:08

I spotted the dried fruit while walking the trail. I had no idea what it was but this site quickly helped me figure it out. The 3 sectioned fruit is unmistakable.

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