Editor's Note: This article was originally published on October 26, 2010. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
At first sight I thought I had morning glories vining up through my daylilies. I gathered small branches that were always finding their way into my yard, and gave my "morning glories" a stake of their own to climb. They grew to great lengths, much taller than my tallest daylilies, but when they started to bloom, those tiny little greenish flowers looked nothing like morning glories. I was rather furious when I realized what that vine really was; the wild yam had followed me all the way across Kentucky and was now flourishing among my daylilies. That was the very same vine that caused numerous scraped knees and breathless moments when I did a face plant in the middle of Mom's flower bed. It never failed to wrap itself around my ankles and once there, yank hard enough to throw my feet up and my face down. And here I was, obviously in the middle of adulthood, and it had tricked me again. I could not believe I had been lovingly providing stakes for it to grow up on.
Not at all closely related to the look-alike morning glory (Ipomoea spp.) , and definitely not similar to the sweet potatoes or yams that figure in the traditional Thanksgiving dinner, wild yam root (actually a rhizome) has a disagreeable taste and a vine that is too tough to break easily. Actually, it has an excellent history among herbalists, so in spite of my battle with it, I am going to give it due respect for its historical place in the world of herbal medicine.
Growing mainly in the central and southern parts of North America, wild yam once played a prominent role in folk medicine in the United States. Preparations from the boiled root were taken by Indian women to relieve the pains of childbirth and were recommended as a diuretic, emetic, expectorant, and remedy for colic and muscle spasms. Some esteemed it especially as a treatment for rheumatism.
Dioscorea villosa grows in damp woodlands and thickets, and I must admit, it grows well among my daylilies. Its range is from New England west to Minnesota, south to Georgia and Texas. The species is threatened in Rhode Island. It is a perennial vine climbing to 20 feet. It has heart shaped alternate leaves, hairy on the under surface, that are borne singly along the slender stem. Its flowers are greenish white, very tiny and are borne in loose clusters. The flowers bloom in June and July. The seed capsules are really interesting, and are great for fall arrangements. However, I do not let the plant grow long enough to produce seed pods. The seeds form in yellowish green winged triangular capsules.
In the early 1900s scientists began searching for plant sources for such steroids as cortisone and some hormones, because the cost of isolating these substances from animal sources was prohibitively expensive. Eventually researchers discovered steroidlike substances in the wild yam plant and in related species. Today quantities of the species are collected in the wild or cultivated in Mexico to supply diosgenin, the basic substance from which birth control pills and several other steroid drugs are made.
I will tell you this: if the pharmacologists ever run out of wild yam, I am going to eagerly let them know that wherever I live, wild yam will grow in massive abundance. It continues to take great joy in being my downfall, right in the middle of my daylilies. I have wondered how it got here, all the way across and on the other side of Kentucky. And since none of my neighbors have it in their gardens, I have to believe that its following me here was deliberate.
The truth is, when I brought the two little eastern red cedars from southeast Kentucky to my garden here in western Kentucky, they both came complete with a root ball. I suspect cleavers and wild yam came along for the ride in the root balls. It is a good thing that my daylilies don't seem to mind.
Photos in the article are from Plant Files, thanks to Julie88 and Arsenic. The last photo is from Wikipedia's Public Domain.
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