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The Amazing Ginkgo

Evolution and Ancestors

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Evolution and Ancestors
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The species ginkgo biloba is a seed-bearing tree,

sometimes referred to as a gymnosperm. Gymnosperm means

“naked seeds”. (Campbell, Reece &, Mitchell, 1999, p.564)

The seeds lay on the cone scales, (Encyclopaedia Britannica,

1987, p.505) or at the end of stems, as opposed to angiosperms,

whose seeds are inside fruit. Conifers, such as pine trees, and

cyads, which look like palms, are also gymnosperms.

Gymnosperms developed from seedless vascular plants

(progymnosperms), such as horsetails and ferns, which had

become widespread during the Devonian period (Lippert, 2002).

The progymnosperms did not have seeds to begin with. Seeds

developed in these plants during the late Devonian period, which

allowed plants to grow far from sources of water. (Lippert).

     At least two species of the order Ginkgoales, can be found in

the Permian period, 270 million years ago. (order) Ginkgoales

proliferated, and five or six species appeared during the middle

Jurassic period. The widest diversity occurred during the

Cretaceous period, in areas that today are Asia, Europe and North

 America, when up to eleven species existed. There is

disagreement as to how many species actually existed. The order

Ginkgoale decreased to one species called gingko adiantoides,

during the Paleocene epoch. It is hypothesized that the extinction

of dinosaurs and some reptiles lead to this decrease in diversity,

since it it believed these creatures spread the (order) Ginkgoale

seeds. Some say they may have died off due to the ice age.
Some say they may have died off due to the ice age.The species
gingko adiantoides, appears to be almost

identical to the ginkgo biloba species which lives today.

(University of California Museum of Paleontology, p.1)  The fossil

record in North America stops at about 7 million years ago, and

from Europe about 2.5 million years ago. The species, Gingko

biloba was thought to be extinct, until in 1691, the German

physician and botanist, Engelbert Kaempfer discovered it was

growing in Japan. It seems Buddhist monks in China had been

growing the tree by their temples since 1100 AD. It spread by

seed, and continued to be planted by Buddhist monks, to Japan and

Korea. Ginkgo seeds were brought to Europe in 1700’s, and later

to North America. http://www.xs4all.nl/~kwanten/history.htm

     There continues to be a debate as to how to classify gingko

biloba. Some botanists associate the (order) Ginkgoales with

cycads. Others believe they belong in the conifer group. The

difficulty arises from the fact that ginkgoes are similar

reproductively to the cycads, and structurally like

conifers.(University of California Museum of Paleontology, p.3)  

The (genus) ginkgoes are differentiated from other gymnosperms

by their fan shaped leaves and dicot-like leaf venation.”(University

 of California Museum of Paleontology,) Paleozoic (division)

gynkgophyte leaves were divided into numerous small sections.

During the late Cretaceous period, the leaves became four lobed.

ginkgofossil2taggart.gif

Modern ginkgo biloba species’ leaves are generally bilobed,

however, they can vary greatly, even on the same tree.

See both web of the following links for source of varied leaf shapes photo below.

leafvarssm.jpg

Ginkgo biloba grow up to 30-40 meters tall and live for 1,000 years. (University of California Museum of Paleontology) Some sources say the oldest tree in China is 3,500 years old. The tree has a tall slender shape until it becomes older. As the tree ages, it produces growth from the roots which become additional trunks, as well as growths which drop down from the upper trunk and branches, which take root when they contact the ground.(chi-chi)

ginkgofossiltaggart.gif

gingkowithchi.jpg
http://www.xs4all.nl/~kwanten/the

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