SCIENTIFIC NAME: Ginkgo biloba
This tree in Colorado: The Ginkgo is a very unique tree, it is a “living fossil”, being one of the oldest trees around. Its origin dates back more than 170 million years ago when the dinosaurs roamed. The tree is a gymnosperm meaning the seed is not in an ovary. Gymnosperms include pines, spruces, junipers, and cedars which have needle or scale-like leaves. This tree is the only species of the Ginkgoaceae family remaining. Once widespread in Europe and North America, most died out during the Ice Age. Surviving trees were found in China. If it were not for their preservation by Buddhist Monks, these trees would likely have gone extinct. None exist in a wild state.
The tree was rediscovered in 1691 and brought to the United States in 1784. It is now found throughout the country and have been successfully planted in Colorado communities. The State Champion tree is in Canon City, the trunk is 25 inches in diameter and it is 65 feet tall. They also can be found throughout the world. In Santiago, Chile they are found as street trees in the downtown area and doing very well.
The tree tolerates and survives almost all adverse conditions including drought, heat, air pollution, ice storms, and poor soils. It is virtually free of insects or diseases.
There is one negative feature to this wonderful tree. There are male and female ginkgo trees. The fruit, which is only on female trees has a disgusting and rancid smell. Some call it a stink-bomb tree. You do not want to have a female tree!
Growth rate, form and size: Moderate growth but slow until becoming established; 12-18 inches of leader growth per year. In youth the tree is gawky looking. Pyramidal and columnar in form with spreading branches that are sparsely branched as it matures. Mature height of 50-65 feet and a 25-35 foot spread but some trees up can grow up to 75 feet wide.
Foliage: Unique fan shaped and ribbed leaf with dent in the middle. They are up to 3 inches wide and have a 3 inch petiole. The species name biloba means two lobbed. Leaves are a lighter green in the summer turning an attractive bright yellow in the fall. They flutter in the wind like quaking aspen.
Flower and fruit: The flowers are inconspicuous and the fruit is 3/4 -1/1/2 inches in size and tan in color. Due to an obnoxious odor of the fruit, only the male tree should be planted. Trees are propagated by cuttings from male cultivars.
Bark: The trunk is light brown to grayish brown, deeply furrowed and highly ridged. Again, it is unique when compared to most other trees.
Insects and diseases: Because this is such a unique tree, no serious pests have been observed on this tree in Colorado.
Landscape value: It is a good specimen or focal point tree to have in a yard and is commonly used as a street tree. It is tolerant of poor soils and air pollution which makes it highly suitable for urban areas. It is also resistance to snow and ice damage. It is long-lived.
National Arbor Day Foundation
Steve Nix: About.com Forestry Tree help
Photo credits: Vince Urbina, CSFS Forester, SelecTree from Calpoly