The Ginko Biloba, also known as the Maidenhair Tree, is apparently a living fossil. Living fossil is an informal term for any living species which appears similar to a species otherwise only known from fossils and which has no close living relatives. The one we are familiar with, that has fan shaped leaves, is the only variety left growing on the earth, although there were many other ginkos in earlier times and they're preserved in the fossil record. You may have heard that Ginko can be taken to enhance memory and slow dementia but there is apparently little scientific evidence to back up this claim.
The Ginko is an unusual tree and is apparently more closely related to ferns than to trees because it reproduces through sperm which actually "swim" to the flowers for fertilization, much like ferns, mosses and algae. You can read more about the tree and this amazing form of reproduction here.
The slide show below is of our ginko tree, which was planted about 8 years ago. These photos were taken over a period of two weeks. The last two pictures were taken in the past two days. It's another interesting thing about ginkos, they tend to drop all of their leaves rapidly, within just a few days. When I was a student at UNC Chapel Hill in the late 70's there was an ancient ginko tree on campus and each fall there was a contest to guess "when will the ginko drop its leaves?" Aside from the unique fan shaped leaves, my favorite thing about this tree is its transition from deep green to gold, sometimes it seemed it turned more golden over the course of a single day. And the pale yellow field of leaves on the ground once the tree is bare is almost as lovely as the sight of the tree as its turning.