AR Gardener Magazine
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Ginkgo biloba, Ginkgo, Maidenhair Tree
On my desk sits a fossil ginkgo leaf obtained from the badlands of the
Dakotas. The tree grew during the epoch period when dinosaurs roamed the great
shallow inland sea that made up the heartland of this nation. Darwin called
species such as the ginkgo living fossils, a kind of enduring telegraph line
from a past age to the present. Today Ginkgo biloba exists as a monotypic
species first appearing in fossil records of the Triassic period of the Mesozoic
era about 225 million years ago. It was widely distributed throughout the world
with fossil ginkgo leaves found in Europe and our western states. Ginkgo
apparently lost its worldwide dominance about the time the dinosaurs died off,
but fortunately for gardeners, it did not become extinct but instead found a
sheltered homeland in China.
Nearly every schoolchild can recognize the unique fan shaped ginkgo leaf,
because it stands alone in the plant k ingdom with nothing even closely
resembling it. Ginkgos are big trees that attain great age. The largest ginkgo I
know of in Arkansas is one growing in the alluvial bottomland not far from the
Arkansas River in Pine Bluff with a trunk diameter in excess of 6 feet and a
height approaching 100 feet. The tree is a conifer, yet unlike pines, it loses
its leaves when autumn arrives. The leaves turn a beautiful golden yellow in
late October and then, as if awaiting a signal, fall to the ground within a few
hours.
Ginkgo is a dioecious species having individual trees that are either male or
female. Flowers do not appear for about 20 years, so sexing the trees by waiting
for flowers is a long time investment. On short fruiting spurs female trees
produce a cherry size glaucous, yellow-orange, fleshy fruit that stinks to high
heaven when ripe and crushed under foot on the sidewalk. During a good year the
trees produce a bumper crop of fruit which are considered a tasty but stinky
delicacy by the Chinese and Japanese. The large seed is eaten, not the fruit. Of
the roasted seed, the USDA plant explorer Frank Meyer observed in the early part
of the 20th century "the flavor does not appeal to the palate of the Caucasian
race".
The problem with stinky fruit can easily be avoided by planting grafted male
trees such as ‘Autumn Gold’, the most common of the male clones. Planting
isolated seedling trees of unknown sex seems like a possibility because wind
borne pollen distribution over great distance seems unlikely. But this problem
suffers from several problems. First, I’ve found no indication how far the
pollen will spread. Female trees separated by at least two blocks reliably
produce fruit here in Fayetteville. Secondly, it is impossible to predict when a
neighbor will plant a male clone in your vicinity and restore the fecundity of
your spinster tree.
In China ginkgo has been cultivated for about 1000 years, making it a
Johnny-come-lately amongst that nation’s storehouse of cultivated fruit trees
such as peach, apricot and jujube. It made its way to Japan during the Southern
Sung dynasty (1128-1279). The widespread appearance of 600 to 1000 year old
trees in Buddhist and Taoist temples in China and Japan is a reflection of the
long term stability of these holy places and the general reverence that Asian
cultures place on venerable old trees, not to any particular religious
significance. The romantic myth that ginkgos endure in only temple grounds is
just that, a myth. The trees occur wild in southern China in the Guizhou and
Anhui/Zhejiang border region.
The Western world learned of the ginkgo when Dr. Engelbert Kaempfer
(1651-1716) wrote his History of Japan after being stationed there as an
employee of the Dutch East India Company. By the 1730's ginkgos were growing in
Utrecht Botanic Garden in Netherlands. It was an instant favorite and spread
rapidly, becoming one of the first Asian trees to be widely planted in Europe.
By 1784 it had made its way to the US to the estate of William Hamilton in
Philadelphia.
Ginkgo has found new appeal throughout the world because from it is
manufactured the modern day "smart pill". Ginkgo leaves, grown in plantations in
Virginia, are shipped to Germany where the Ginkgo tablets are made. Clinical
trials and testimonials abound about the effectiveness of this leaf extract in
improving short and long term memory. Trials suggest that the effectiveness of
the drug comes from improvement in cerebral and peripheral blood flow and
increased oxygenation of brain tissue. In the past decade Ginkgo based herbal
medicines have been in the top 10 in worldwide sales.
Every school yard and city park should have a ginkgo planted amongst its
maples and oaks. However, the average homeowner may be a bit impatient with the
slow growth rate of the tree. Sixty year old ginkgos here in Fayetteville have
trunks about 18 inches in diameter and heights of 45 feet. A 20 year tree I grew
from seed has a 6 inch caliper trunk and is about 20 feet tall. But if you are
planting for the future, a ginkgo is a wonderful tree that will grace any garden
and grow in any reasonable soil for centuries to come. Ginkgos are completely
pest free, a clam that can be made of very few trees.
This story first appeared in the
AR
Gardener Magazine.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Tree Profile - October 2002
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