^^^Grape vine and grape wood is perfectly fine for aquarium. Cleaning and soaking is absolutly key in adding driftwood to a tank.^^
The drift wood will sink slowly as the bogging process isnt instantanious. But to be safe and not sorry, soak in a container or attach to a heavy object.
Wood to avoid is eucalyptus, and any vine of a plant known to be toxic such as Sumac, Oliander etc. I have heard conflicting opinions though on "real" or natural drift wood. Some say that in the wild, fish dont have a choice as to what wood falls into their water and they survive. I say, receiving water is moving any toxins away much better than in an aquarium. I have seen Eucalyptus in aquariums and the tank inhabitants were fine. To each his/her own, but I excersize caution and dont use Eucalyptus.
Just my 2¢