Heard It Through The Grapevine

Does anyone know where the phrase "heard it through the grapevine" came from?
Thanks!

From the archives:

".grapevines were associated with telegraph lines somewhere along the line, for by the time of the Civil war a report by 'grapevine telegraph' was common slang for a rumor. The idea behind the expression is probably not rumors sent over real telegraph lines, but the telegraphic speed with which rumor mongers can transmit canards with their own rude mouth-to-mouth telegraph system." From the Encyclopedia of Word and Phrase Origins by Robert Hendrickson (Facts on File, New York, 1997).