THE NATURALIST PAGES:
TREES
The trees/shrubs described here are distinctive in their own way (good or bad). They can be seen in the Toronto area and, except for the Black Walnut, are usually easily recognized.
Note:These pages often make use of linked-to pictures so the pictures may take a while to load, or may not load at all at the first time, depending upon the source. Let me know of any difficulties encountered.
More (Sycamore, Linden, Alder, Beech, Hemlock, Locust)
I found this solitary tree in a vacant, weedy, industrial lot nearby to a Home Depot store in Toronto's east end (East York). It had quite a distinctive appearance with its foliage clinging closely to its upward rising branches. Coupled with its unusual general appearance was the strange shape of its leaves. It resembled no other tree in the neighbourhood!. The particular tree is fairly large, about 35 feet tall and its trunk is about 22 inches in diameter. After some investigation I found that it was a Ginkgo biloba tree - and a female at that!. I have to conclude that the fate of this tree, upon re-development of the lot, is precarious at best. Note: as of November, 2002, the lot is still vacant and the tree still stands!
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 (from same tree) |
History
The Ginko biloba tree is a unique tree and is reportedly the oldest tree species on earth. It Evolved from fern-like ancestors and is the last remaining species of a tree that has managed to survive over ages of time. Fossil patterns of its leaves have been found in rocks dated at over 150 million years. Individual trees have been known to live 1,000 years. An excellent specimen in Kew Gardens, London, England is one of the original trees dating from the founding of the Gardens in 1760. Another specimen at the University of Oslo, Norway was planted in 1870 and is still doing very well despite the Northern latitude.
The science of fossil study - palaeontology - plays an important part in the history of the Ginkgo biloba. The tree was originally known only through fossil records. The records told us that at one time there existed such a plant but with no apparent living evidence it was assumed that the tree, like the dinosaurs, was extinct.
The preservation of the Ginkgo came about in the mountains of China were a few of them were cultivated in Buddhist temple gardens. By about the 12th century the Ginkgo was brought out of the mountains and spread throughout temperate Asia. It wasn't until the 17th century that western travellers discovered the Ginkgo and eventually introduced it to Europe.
The tree was introduced into North America in the 1700's. This was actually "re-introduction" because, in prehistoric times, the species was widespread over the northern hemisphere. Fossil evidence of the tree has been found in a number of places in North America including British Columbia.
Over the past 10-20 years the Ginkgo has become a commonly planted ornamental tree in Toronto because it is somewhat resistant to urban conditions. There are many of them (males) planted in parkettes and along some of the streets. So far I have come across five relatively young specimens planted in east Toronto parks. I have yet to find another one as large as our neighbourhood tree.
Note: Since originally preparing this page I have managed to find a few more mature female Ginkgo's - Two in Toronto's High Park; one in the Niagara Park's Botanical Gardens and a couple in Toronto's Edwards Gardens.
The name
The name "Ginkgo" comes from the Chinese "Yin Hsing" meaning "Silver Apricot" - alluding to the mature "fruit" of the tree. The leaves of the tree are very distinctive, being fan-shaped with a leathery texture with very fine straight veins and, in some cases having two lobes (thus the name "biloba). No other tree has these fan-shaped leaves. The summer leaves are light green in colour but turn to a brilliant lemon yellow in the Autumn and, peculiarly, almost all are shed at the same time (sometimes in a single day).
Another name for the tree is "Maidenhair tree" referring to the similarity between its smooth green leaves and those of the maidenhair fern.
The Japanese have still another name for the Ginkgo that comes from the shape of its leaves: they aptly call it `I-cho', meaning "The tree with leaves like a duck's foot."
General characteristics
The Ginkgo is a very slow-growing, but tall, tree. It can reach a height of 80 feet or more and will take from 20 to 30 years before bearing fruit (more on fruit-bearing to follow). It is reported to be a very hardy tree that is highly resistant to pollutants, insect pests, and disease, although there is apparently some evidence that the Ginkgo is now also suffering damage from air pollution.
Mature Ginkgo biloba
University of Delaware, Botanical Garden.
©John Frett
Ginko reproduction
Ginkgo trees are separate male and female. In the spring the male produces catkin-like "cones" that release sperm-bearing pollen to be carried by the wind. The female tree in turn produces a yellow "fruit" that is shed with the leaves in the fall (The specimen that I came across is bearing fruit and therefore must be a female tree). The fruit of the tree takes on a foul odour as it lies rotting on the ground.
(Note that what we think of as the "fruit" of the Ginkgo is really defined to be a "seed" by the botanists, but since it looks like a "fruit" to most of us amateurs we'll leave it at that.) Although the female fruit picks up the pollen while still on the tree, actual fertilization of the egg contained within the fruit must wait until the fleshy part of the fruit has rotted away to provide access to the egg. Thus fertilization may not happen until the following spring. A truly solitary female tree simply produces infertile "fruit" that rots on the ground and this is very likely the situation with the tree I happened upon.
The nut within the fruit of the female tree is edible - when properly collected and prepared.
Because of the unpleasant smell from the rotting fruit of the female tree, most nursery-cultivated trees are male, being derived through cuttings from male trees only. The smell of the fruit is not unpleasant while it's on the tree and this "smelly" situation is not really serious if the fruit is simply harvested when it falls. The city of Ames, Iowa adopted this approach and it seems to have worked out well (probably an economic plus, since a "Festival" was born). In addition the female tree doesn't bear fruit until it's about 20 years old!
THE GINKGO HAS COMPANY! - THE DAWN REDWOOD
Up until about the early 1940's the Ginkgo stood alone as a living fossil relic of past ages. At that time a discovery was made in china of another living fossil tree that had previously also only been known through fossil records and was thought to be extinct. The tree is the Metasequoia or "Dawn Redwood" The story is best sumarized in a Nature Bulletin published by the Forest Preserve District of Cook County, Illinois in the winter of 1996.
Click here for a side trip to the bulletin.
So far I have managed to find three mature Dawn Redwoods - In Toronto's High Park, Edwards Gardens and in the Niagara Park's Botanical Gardens. These are very large trees and I've been told that the Niagara and Edwards Gardens trees are from the original stock "rescued" from china. They are thus at least 50 years old.
Here aretwo pictures of Ginkgo and Dawn Redwood fossils found in British Columbia. They are dated to be from the Middle Eocene period (40-50 million years ago). Ginkgo biloba Metasequoia (Dawn Redwood)
Maidenhair tree An excellent treatise on the Ginkgo tree. Text ranges from highly technical to that for us amateurs! Includes the Ginkgo Petrified Forest State Park at Vantage, Washington. It also discusses the Dawn Redwood - Palomar College, San Marcos, California.
Morphology Part of a scientific journal with pictures of male cones and female "fruit". There is much more to this site. Explore it even if only for the pictures!
The Ginkgo pages! An excellent and exceptionally complete website on this remarkable tree by Cor Kwant
China Dawn Redwood in China and
The Flora of China
Note:
Bristlecone THE ANCIENT ONES! A side trip.
Martyr THE MARTYRED ONE! An unfortunate story.
Middle Eocene period
British Columbia
Middle Eocene period
British Columbia
Above photographs of fossils with permission from
Fossilfinds
© W. Banner
This site covers a broad spectrum of natural phenomena and is well worth a thorough exploration.
Although the Ginkgo is probably the oldest tree species on earth it is not the oldest living tree on earth. This record is held by the trees of the Ancient Bristlecone Pine Forest in the White Mountains of California. An interesting side trip is provided in the following two links: