Download Ginkgo biloba - San Diego Master Gardeners

Ginkgo biloba
Phylum: Ginkophyta
Family: Ginkoaceae
Genus: Ginko
Species: G. biloba
Common Name: Maidenhair Tree
History:
The Ginkgo tree is a living fossil, a tree that has remained mostly unchanged since the lateJurassic period, or 65 – 200 million years ago. G. biloba is the only remaining species of the
phylum; therefore, it has no relatives. The Ginkgo tree is one of the oldest cultivated trees,
with dating back to 1,500 years ago in China. Widespread in China, Japan and Korea, it was
first noted and brought to Western civilizations in the early 1700’s.
Plant Structure:
Ginkgo is a gymnosperm or “naked seed”, so there is no fruit surrounding the seed, and neither
a monocot nor a dicot. There are four groups of non-flowering plants: cycad, ginkgo,
gnetophytes and conifers.
Ginkgo’s leaf is distinctively fan shaped, generally double lobed and 1-4 inches wide. The leaf
ranges in shades of green but turns spectacularly yellow in the late fall, keeping its leaves until
first frost and then shedding all quite quickly, creating a yellow carpet on the ground.
The tree is dioecious, with separate male and female plants. Pollination is carried out by wind.
Propagation commercially is for the male plant grafted onto rootstock, as the female creates
wet, messy seed that is reported to smell strongly like vomit and difficult to clean up.
Site Conditions:
Ginkgo is well known for its resilience to poor soil and air quality, which may partially explain
why it has survived for so long.
While it prefers sandy loam, Ginkgo will live and thrive in almost any soil texture and a wide
range of soil pH.
It thrives in regular watering but is drought resistant and needs little water once established.
Long established in Seoul, Tokyo, and dozens of cities in China, it has excellent smog tolerance.
Ginkgo is salt tolerant, grows in USDA Hardiness Zones 4-9, and can grow in full sun to
partial shade.
It is an approved street tree by the City of San Diego, especially for parkways and cutouts.
Fire Safe San Diego rates it as a fire resistant tree and is recommended for defensible space.
It cannot be grown in the desert, Sunset zones 11 and 13.
Growth Habit
Gingko grows upright and turns into an umbrella canopy with age. Its height can reach 35-60
feet, and the City of San Diego rates it to 40 feet generally in this area. Its width is 25 feet.
The bark of a young tree is light green and turns light gray to dark gray with age, fissured.
It is rated moderate in shading capacity and is deciduous, dropping leaves in late fall or early
winter. Its leaves can range all shades of green on a single tree and is very beautiful.
The growth rate is slow, generally 1-2 feet per year. Trees are long-lived, 150 years or longer.
A Gingko biloba in Sacramento is registered as a California Big Tree, measuring 84 feet high
with a crown spread of 77 feet (age unknown).
Varietals:
Many varietals have been introduced, including “Jade Butterfly”, “Autumn Gold”, “Beijing
Gold” and more. Varietals are bred for dwarf size, fall leaf color, and variegated leaf color.
Pests and Problems:
Gingko is resistant to oak root fungus, phytophthera cinnamomi, and mistletoe. It is
susceptible to anthracnose, root nematodes and wood decay fungus, particularly turkey tail
fungus. Overall, it is a hardy tree. Its leaves are highly acidic and insect resistant.
The seed from the female plants attract squirrels and rats.
Medicinal Uses:
For centuries in China, the seed has been used medicinally; however, today in Western culture
it is the Ginkgo Biloba Extract (GBE as listed on supplements) from its leaves that is used
primarily. GBE is reported to increase memory, capillary blood flow, and many other claims.
The supplement does have several drug interactions and it should be reported to your doctor if
you are taking it. In the home garden, growers should never consume any part of the seed, as
parts are toxic.