There are many trees on the campus of the University of Illinois at Urbana-Champaign, but certainly the most noticeable is the ginkgo tree. The fan-shaped leaves litter the ground when autumn comes, and they are only just starting to change to yellow. They stretch up as tall as three stories, and when you look out at them from a third floor window, it looks almost like a primeval forest.
Ginkgos are genetically primitive trees, and the particular species of the tree, Ginkgo biloba, is the last surviving member of its genus. If you look at a ginkgo fossil, you will find that the leaves have not changed much, even though the fossil is from thousands of years ago. They are the only seed plants that do not have a network of veins in their leaves; instead, the veins in a ginkgo leaf spread out like a fan. Some of them branch off from each other, but they do not reconnect further on in the leaf.
If you see a ginkgo tree in an area where there are buildings, it is most likely a male ginkgo. Ginkgo trees have separate sexes, and most people tend to plant male trees, because the female trees create a rancid odor in spring. They make ovules rather than pollen cones, which the males make, and when pollination occurs, the females form a seed. The seeds have butanoic acid in them, which produces the rancid smell. (Butanoic acid, which comes from the chemical compound butane, was named that way because the compound is responsible for the smell of rancid butter. Butter, but-ane.)
Plants in the ginkgo genus were originally spread around the world, but many died out, and Ginkgo biloba was left in China. It is believed that Chinese monks preserved ginkgo trees in their area, since most ginkgo trees in that area are extremely genetically similar, suggesting a long period of cultivation and breeding within a small population. The tree eventually spread back around the world, and can be seen in most temperate climates, but its origin stems from China. It is an extremely long-lived plant, and it is rumored that the oldest ginkgo recorded was around 2,500 years old.
Ginkgo trees can be seen in many places around Illinois. They are spread all over UIUC's campus, and perhaps there are some in your hometown. The Morton Arboretum in Lisle, Ill., has many ginkgo trees, and its logo used to be a ginkgo leaf. Look for fan-shaped, bright yellow leaves in the fall, and perhaps you will find a ginkgo.