Ginkgo

Ginkgo (Ginkgo biloba) is a non-flowering tree known for its distinctively-shaped leaves which turn to a deep yellow color in fall and drop over a short period, carpeting the ground below. The tree, examples of which appear as early as the Middle Jurassic epoch, is considered a "living fossil. It is the sole surviving genus of the Ginkgophyta division of the clade Gymnospermae.

Through prehistoric relatives of ginkgo have been found on other continents, modern ginkgo trees are endemic to China. They are rare in the wild, and were once thought extirpated. The most diverse examples have been found near Tibet, with some specimens apparently pre-dating human settlement in Korea and Japan. Historically they were known in Chinese as 銀果 (meaning "silver fruit"), pronounced yínguǒ in Mandarin. In Japanese, the name is pronounced as "gin kyo". European scholar Engelbert Kaempfer, using Japanese scholar Tekisai Nakamura's 17th century manuscript Kinmō Zu'i, described the plant in his 1712 book Amoenitatum exoticarum. His work was published in Latin, and used spelling "Ginkgo". That spelling was picked up by naturalist Carl Linnaeus for his 1771 book Mantissa plantarum II, adding the specific name "biloba", Latin for "double-lobed".

Ginkgos grow commonly to over 100 feet tall with some specimens in China exceeding 165 feet. Its crown is angular or cone-shaped with large, long, erratic branches. Its roots are deep and help the tree to resist damage from wind and frozen ground. It thrives in a range of soils and prefers full sun. The plant is exceedingly resistant to infestation, disease and pollution. There is little evidence of senescence, with some trees appearing healthy after reaching up to an estimated 2,500 years old. Ginkgo leaves are uniquely fan-shaped, marked by radiating veins, with rounded lobes.

Ginkgos reproduce by more than one means. They are dioecious, with distinct sexes. Male plants produce pollen cones, which pollinate ovules on female trees, usually by action of the wind. Actual fertilizations is by means of motile sperm. Fertilized ovules form seeds which are encased in a fleshy shell, given a pronounced rancid odor by the presence of an ester of butyric acid. The tree can also reproduce by forming aerial roots which, if planted, produce clones. The ginkgo genome is extensive, with more than 3 times as many nucleotides as the human genome, though much of it appears reduplicative.

Ginkgos have long been cultivated for their appearance. The trees are revered in Confucianism and Buddhism, and have frequently been planted at temples and shrines, as well as in learning institutions. They are popular in bonsai, and have also been frequently used as ornaments to residences and as street trees for many centuries. They have been cultivated around the world, but not appreciably naturalized outside of Asia. The tree was introduced to North America by French botanist André Michaux

In many cases, only males trees are planted, in order to avoid the nuisance of rotting, smelly seeds. However, the pollen produced my male trees can trigger powerful allergic reactions.

Ginkgos in Birmingham

• James Garrett planted four ginkgo trees at Capitol Park (now Linn Park) in 1884.
• Another large ginkgo, described as "representative of the world's oldest species of trees", was planted on the east side of the park after completion of the new Jefferson County Courthouse in the early 1930s.
• Several ginkgos planted around Munger Hall and the Stockham Building at Birmingham-Southern College became associated with the school. Retiring faculty and graduating students have spread seedlings from those trees across the country.
• In the 1980s, rows of ginkgo trees were planted on 2nd Avenue North in downtown Birmingham as part of the city's urban tree planting project, guided by Nimrod Long & Associates.

References

• Ervin, Mark (December 1, 2016) "Birmingham in Bloom: An Analysis of the 2nd Avenue Ginkgo Trees" Big Communications
• "Ginkgoes in Birmingham" (Fall 2020) 'Southern magazine, Vol. 45, No. 1, pp. 24–25
• "Ginkgo biloba" (June 13, 2024) Wikipedia - accessed June 18, 2024