Grapes are one of the oldest fruits that mankind has cultivated and grown. According to Grapesweb.com, scientific evidence suggests that grapes grew wild in prehistoric times. Mankind's attempts to tame grapes and grow them date back to at least 6,000 B.C. Scientists believe that grape cultivation started in prehistoric villages in Asia near present day Georgia and then spread south along trade routes into Iran. Today there are over 5,000 species of grapes grown for wine. However, these varieties are known by approximately 20,000 different names. The science of identifying grape plants is known as ampelography.
Examine the vine that you suspect may be a grape vine. Characteristics of grape vines include tendrils that wrap around anything that the plant encounters and help the plant climb, leaves with shallow lobes and toothed edges that grow alternately on the stem, and clusters of small, dark, sweet, edible fruit.
Photograph the vine to record the plant's characteristics. Select a digital camera with a macro setting so that you can take detailed photos from just a few inches away.
Read books on grapes to learn more about the characteristics of each variety. You can find books on grapes at your local library, or through interlibrary loan.
Compare your photos to photos of various grape varieties. The variety that most closely matches your photographs is probably either the same species of grape or a hybrid of the same species.
Contact an agent from your local land grant college's community and continuing education extension service for a more precise identification of your plant. Many land grant colleges have staff that are knowledgeable in the field of ampelography, particularly in states such as California where wine-growing is a commercial enterprise. You can e-mail photos of your plant to the extension service for quick identification.
Post photos of your plant to online grape forums such as the one at Winepress.us. These forums are frequented by grape growing and winemaking enthusiasts who may be able to identify your plant species.