Tree Profiles: Ginkgo, Part 2 (Ginkgo biloba)
This is the first of a two part series on the ginkgo tree. The following examines the tree’s root development, soil & topography, cultivation, damaging agents and pests, allergenic potential, hardiness, and uses.
The ginkgo tree (Ginkgo biloba), also known as Baugio tree, fossil tree, Japanese silver apricot, maidenhair tree, and yinhsing, is the oldest recorded tree species on Earth. Fossilized ginkgo trees have been discovered that date back 270 million years. Ginkgo is the only surviving tree to be classified in the division Ginkgophyta.
The ginkgo tree is native to China. It was first described by Carl Linnaeus, a Swedish botanist, in 1771. Its name is a mistranslation of the Japanese word gin kyo, which means silver apricot. Ginkgo is widely cultivated in North America, Europe, and Asia. It is renown for its characteristic fan-shaped foliage, resplendent autumn color, and general hardiness. Many herbal supplements are derived from Ginkgo, and used to treat various maladies.
Ginkgo trees establish deep root systems, which provide them with ample structural support. This enables ginkgo trees to adapt to a myriad of settings. Ginkgo trees may be found in locations ranging from cliff edges to river banks. Mature ginkgo trees can sprout aerial roots on the underside of large branches. They will generally do so in response to environmental disturbances, or when the tree has incurred extensive damage to the crown. The aerial roots anchor the tree, allowing it an opportunity to recover.
Soil & Topography
The ginkgo tree prefers moist environments, with soil that is well-drained. It can flourish in confined soil spaces, making it an ideal selection for bonsai. The ideal soil pH for the ginkgo tree is 5.0 to 5.5. The ginkgo tree is tolerant of shade.
The ginkgo tree is frequently selected for cultivation. Some of the most popular cultivars include ‘Autumn Gold’, ‘Golden Colonnade’, ‘Golden Girl’, ‘Halka’, ‘Liberty Splendor’, ‘Magyar’, ‘Presidential Gold’, ‘Princeton Sentry’, and ‘Santa Cruz’.
Damaging Agents and Pests
Gingko trees exhibit a strong resistance to insects and disease pathogens. They can also withstand heavy winds, and damage from hail, ice, or snow.
Ginkgo leaves and the outer layer of the seeds (the sarcotesta) contain ginkgolic acids, which can cause dermatitis in vulnerable people, as well as a slew of other allergenic symptoms, including blistering, headaches, and indigestion. When consumed in large quantities, the seeds can be toxic. Male ginkgo trees are highly allergenic, rating 7 out of 10 on the OPALS allergy scale. The female trees are mildly allergenic, with an OPALS allergy scale rating of 2.
The gingko tree is one of the hardiest trees on Earth. It has survived harsh climates, and great calamities. In a testament to its vigor, six ginkgo trees survived the decimation of Hiroshima, Japan during World War II.
In North America, Europe, and Asia, ginkgo is widely sold in tablet and capsule form. The leaves can be ground down, and steeped in water to make tea. Ginkgo extract is a primary ingredient in some cosmetics. In China, ginkgo extract is used medicinally to treat various ailments, including dementia, eye degredation, muscle aches, headaches, anxiety, fatigue, leg pain, and tinnitus. It is a prescription herb in Germany. Ginkgo extract may help to mitigate symptoms of PMS.
The gametophytes inside of the seeds are esteemed in Asia. They are used in congree, a type of rice porridge that is served on special occasions and holidays. Japanese chefs incorporate the ginkgo seeds into a bevy of recipes. If consumed in large quantities, the meat of the seed can cause poisoning by Gingkotoxin, a nuerotoxin that occurs naturally in ginkgo trees. The ginkgo tree’s narrow frame makes it an ideal selection for bonsai and penjing. The ginkgo tree is the official tree of Tokyo, Japan. Ginkgo leaves can be dried out, flattened, and turned into bookmarks.
Photo courtesy of CC-by-3.0