Ipomoea purpurea Common Morning Glory
Common Morning Glory is the English name because there are others in this genus with different shaped leaves such as Ipomoea sagittata which has arrow shaped leaves. The flowers of this species are not always purple either, they can also be blue, pink and more rarely white. This particular plant could only be described as rampant as it covered an entire fence, some rough ground and was nearly up to the top of a thirty foot tall tree.
It is a native of Mexico and America and the seeds are thought to have an effect similar to LSD when ingested - not a brilliant idea to try since most commercially available seeds are coated with a poisonous mercury compound to prevent fungal deterioration.