Division Ginkgophyta – the Ginkgo or Maidenhair Tree
Here is an entire division with only one member, the ginkgo or maidenhair tree. It is a tree commonly seen in the landscape with a very uncommon story.
Charles Darwin called the ginkgo a "living fossil" an appropriate name since ginkgo fossils date back 190 million years. Widespread during the time of the dinosaurs, they survived the demise of the dinosaurs and continued to live in western North America and other locations in the Northern Hemisphere. As the climate changed over geological time, the ginkgo became less abundant, eventually becoming extinct in western North America and Europe. They survived in China, and have been reintroduced into Europe and North America (California in 1854) where they are a favorite landscape tree for many reasons.
Its seed is not enclosed in an ovary, so it is related to the conifers (recall that Coniferophyta and Ginkgophyta are both in the informal group called gymnosperms). Its leaf looks nothing like conifer leaf though, it is distinctively fan-shaped, making this tree very easy to identify.
STUDENT RESEARCH QUESTIONS:
7. Is the ginkgo tree deciduous or evergreen?
8. Does the ginkgo tree produce separte male and femle trees (dioecious),
or are male and
female reproductive structures found on the same tree (monoecious)?
ON TO NEXT TOPIC: Division Anthophyta (Angiosperms)– the flowering plants