Ginkgo (Ginkgo biloba)
The ginkgo is an amazing tree for several reasons. Often referred to as "the living fossil", the ginkgo is one of the most ancient tree species in the world, known to have existed at least 150 million years before the present. Evidence has shown that ginkgo trees flourished across North America for long periods when the continent was warmer, but today the species is native only to a very small region in southeastern China. The ginkgo is virtually extinct in the wild, because the fruits fall at the end of the growing season and have no ability to remain dormant until spring. As a result, the ginkgo literally depends on man to survive. In fact, were the tree not considered sacred by Asian Buddist monks for the past 5000 years, and carefully grown from seeds and cuttings, it is doubtful that the ginkgo would be with us today.

The reason the ginkgo has been so venerated by the Buddist monks has to do with the chemical constituents found in the leaves and fruit. ginkgo means "white nuts" or "silvery fruit" in Chinese, and female trees at least 50 years old routinely produce bushels of ginkgo nuts enclosed in fleshy green casings. The flesh of the ginkgo fruit is loaded with butyric acid (a constituent of vomit), earning the tree the inglorious name of stinkbomb tree here in the United States. But the nut that hides within these foul-smelling fruits is considered both a prized delicacy and an invaluable food for long life (longevity) throughout Asia. For at least 5000 years Asian peoples have grown the ginkgo for its health-providing nuts, making this species the oldest cultivated nut tree on earth. More recently, the amino acid ginkgolin has been found by researchers to be concentrated in both the nuts and leaves of the plant. ginkgolin has been clinically shown to increase the blood flow to the brain and

improve the memory,
As a result, now thousands of acres of ginkgo monocultures are being grown and mown in the southern U.S. for handsome profits.

But none of this explains why the gingko has been planted extensively in many cities around the world. It turns out that this monotypic genus is extremely pollution tolerant - able to withstand levels of atmospheric contamination that would prove lethal to most other species. Arguably a product of millions of years of growth among highly active volcanoes, the ginkgo now thrives in such smoggy and sooty places as Philadelphia, Washington D.C. and New York City. Other features conducive to urban landscapes include insect and disease resistance and the ability to grow in compacted and infertile soils.

So, is the ginkgo an appropriate tree for sustainable landscapes? Well, yes and no. Unlike invasive species such as the Norway maple the ginkgo will never "escape", because the seeds can never successfully germinate. Thus, a ginkgo must always be planted, and will only influence the solitary patch of ground that it occupies. But should a Ginkgo be planted at all? ginkgos have not been native to North America in several million years. Should we honor the historical fact of their presence and continue to plant them, particularly in places where other trees could not live? Or should we give priority to the plant and animal communities that constitute our current epoch, and consider changing our collective lifestyle so that plants other than ginkgos can continue to live among us? What do you think?

more Ginkgo photos

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