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Mr. Smarty Plants - Non-native, invasive, poisonous Chinese yam

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Sunday - October 16, 2005

From: Nashville, IN
Region: Midwest
Topic: Non-Natives
Title: Non-native, invasive, poisonous Chinese yam
Answered by: Nan Hampton and Joe Marcus

QUESTION:

I found a vine in my yard [central Indiana] which I believe is Dioscorea oppositiflora and I wanted first to confirm my identification and second to find out about edibility [especially of the airborne tubers] and uses. It has single and paired tiny potato like tubers in the leaf axils. the leaves are deeply veined and a deep lobed elongated heart shape. It is fall and I have not observed the inflorescence. Apparently there are several species [subspecies?] of Dioscorea? Thanks.

ANSWER:

Chinese yam or Cinnamon vine (Dioscorea oppositiflora, syn. D. batatas) is a non-native vine introduced from China into North America as an ornamental. Both the tubers and the bulbils (the tuber-like growths in the leaf axils) are edible if cooked. However, the Poisonous Plants of North Carolina database lists the uncooked tuber as toxic. Your description doesn't conflict with that of D. oppositiflora, but we can't absolutely identify a species by description alone. Certainly, we wouldn't want to try doing this if it is something you intend to eat. Note of caution: Get a positive identification of your plant before you eat it!

Although it is attractive, D. oppositifolia (along with two other members of the Genus Dioscorea, D. alata and D. bulbifera) is a fast growing and aggressive vine that is considered an invasive weed in the southeastern United States. For an extensive discussion of the biology, uses, invasiveness, and control measures for D. oppositifolia see this article from The Nature Conservancy.
 

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