Ginkgo biloba (Maidenhair Tree)

Ginkgo Maidenhair Tree

Ginkgo biloba is one of the oldest tree species on the planet and is what is known as a “living fossil”. Ginkgo trees occupy a very special position among plants as they belong neither to the conifers nor to the deciduous trees. Here is our guide to this prehistoric plant with tips on planting, care and use of the ginkgo tree.

I. Appearance and Characteristics 

Ginkgo biloba, commonly known as ginkgo or gingko ( GINK-oh, -⁠goh), also known as the maidenhair tree, is a species of gymnosperm tree native to East Asia. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago, and fossils very similar to the living species, belonging to the genus Ginkgo, extend back to the Middle Jurassic epoch approximately 170 million years ago. The tree was cultivated early in human history and remains commonly planted, and is widely regarded as a living fossil.

Ginkgos are large trees, normally reaching a height of 20–35 m (66–115 ft), with some specimens in China being over 50 m (165 ft). The tree has an angular crown and long, somewhat erratic branches, and is usually deep-rooted and resistant to wind and snow damage. Young trees are often tall and slender, and sparsely branched; the crown becomes broader as the tree ages. A combination of resistance to disease, insect-resistant wood, and the ability to form aerial roots and sprouts makes ginkgos durable, with some specimens claimed to be more than 2,500 years old.

Leaves

The leaves are unique among seed plants, being fan-shaped with veins radiating out into the leaf blade, sometimes bifurcating (splitting), but never anastomosing to form a network. Two veins enter the leaf blade at the base and fork repeatedly in two; this is known as dichotomous venation. The leaves are usually 5–10 cm (2–4 in), but sometimes up to 15 cm (6 in) long. The old common name, maidenhair tree, derives from the leaves resembling pinnae of the maidenhair fern, Adiantum capillus-veneris. Ginkgos are prized for their autumn foliage, which is a deep saffron yellow.

Leaves of long shoots are usually notched or lobed, but only from the outer surface, between the veins. They are borne both on the more rapidly growing branch tips, where they are alternate and spaced out, and also on the short, stubby spur shoots, where they are clustered at the tips. Leaves are green both on the top and bottom and have stomata on both sides. During autumn, the leaves turn a bright yellow and then fall, sometimes within a short space of time (one to fifteen days).

Branches

Ginkgo branches grow in length by the growth of shoots with regularly spaced leaves, as seen on most trees. From the axils of these leaves, “spur shoots” (also known as short shoots) develop on second-year growth. Short shoots have short internodes (they may grow only one to two centimeters in several years) and their leaves are usually unlobed. They are short and knobby, and are arranged regularly on the branches except on first-year growth. 

Because of the short internodes, leaves appear to be clustered at the tips of short shoots, and reproductive structures are formed only on them (see pictures below – seeds and leaves are visible on short shoots). In ginkgos, as in other plants that possess them, short shoots allow the formation of new leaves in the older parts of the crown. After a number of years, a short shoot may change into a long (ordinary) shoot, or vice versa.

Ginkgo prefers full sun and grows best in environments that are well-watered and well-drained. The species shows a preference for disturbed sites; in the “semiwild” stands at Tianmu Mountains, many specimens are found along stream banks, rocky slopes, and cliff edges. Accordingly, ginkgo retains a prodigious capacity for vegetative growth. It is capable of sprouting from embedded buds near the base of the trunk (lignotubers, or basal chichi) in response to disturbances, such as soil erosion. 

Old specimens are also capable of producing aerial roots on the undersides of large branches in response to disturbances such as crown damage; these roots can lead to successful clonal reproduction upon contacting the soil. These strategies are evidently important in the persistence of ginkgo; in a survey of the “semiwild” stands remaining in Tianmushan, 40% of the specimens surveyed were multi-stemmed, and few saplings were present.

Phytochemicals

Extracts of ginkgo leaves contain phenolic acids, proanthocyanidins, flavonoid glycosides, such as myricetin, kaempferol, isorhamnetin, and quercetin, and the terpene trilactones ginkgolides and bilobalides. The leaves also contain unique ginkgo biflavones, alkylphenols, and polyprenols.

II. How to Grow and Care

Sunlight

Plant ginkgo biloba in an area that receives full sun to part shade.

Temperature and Humidity

Ginkgo bilobas are commonly grown in urban sites in many regions, proving their tolerance of a wide range of moisture conditions and temperatures. However, they can struggle in hot, dry climates.

Watering

Water as needed to keep the soil moist, provided the site is well-drained. Moisture is particularly important when the tree is young; it is relatively drought-tolerant at maturity.

Soil

The ginkgo is not fussy about soil type or most soil conditions and will tolerate both acidic and alkaline soil as well as compacted soil. It prefers well-drained sandy soil or loam with a pH in the 5.0 to 8.0 range. They are more tolerant of compacted soil than many other types of trees.

Fertilizing

Young ginkgo biloboa trees can benefit from a spring feeding of tree fertilizer. For the amount, follow the product label instructions. Mature trees typically do not need to be fed.

Pruning

Many types of ginkgo start out narrow while young but then become quite wide as they age, growing into shade trees. You can slow down this process a little by pruning them while young so as to force them to produce a single leader. But a much better solution is to select a cultivar known to have a narrow shape.

At the other end of the spectrum, they are also used for Japanese bonsai.

Propagation

Gingko can be propagated from cuttings. Here’s how it’s done:

  • In May or June, take a 6-inch stem cutting of young wood from a male gingko tree. 
  • Fill a 4-inch pot with potting mix and water it thoroughly until the soil is evenly moist. You can use one pot for a couple of cuttings but leave at least 1 inch space between them. 
  • Dip the cut ends in rooting hormone. Make a hole in the soil with a pencil or stick for each cutting and insert the cuttings in the holes. 
  • Place the pot in an outdoor location in bright, indirect light out of the hot sun. Keep the soil moist at all times but not soggy. 
  • Once one of the cuttings has rooted, cut the other one to the soil level (don’t pull it out, or you will disturb the tender new roots). 
  • When the roots start to grow out of the drain holes, repot cuttings to larger individual pots and let them grow in pots for a couple of seasons. The stronger the sapling is when transplanted, the better its chance of survival in the landscape.

Pests and Diseases

The male trees are preferred (unless you have allergies), because they are fruitless. Female trees bear a fruit-like product, actually a seed ball. It not only emits a foul odor but also is slippery when it drops down on sidewalks or driveways. The problematic “fruit” is about the size of a cherry tomato.

Female Trees Drop Smelly Fruit

Cleaning up after female Ginkgo biloba trees is a high-maintenance task. Fortunately, all-male cultivars have been created through grafting. Buying one of these cultivars gives you a way to experience the beauty of the tree while avoiding the mess.

III. Uses and Benefits 

The wood of Ginkgo biloba is used to make furniture, chessboards, carving, and casks for making saké; the wood is fire-resistant and slow to decay.

  • Culinary uses

The nut-like kernels of the seeds are particularly esteemed in Asia, and are a traditional ingredient in Chinese food. Ginkgo nuts are used in congee, and are often served at special occasions such as weddings and the Chinese New Year (as part of the vegetarian dish called Buddha’s delight). Japanese cooks add ginkgo seeds (called ginnan) to dishes such as chawanmushi, and cooked seeds are often eaten along with other dishes. Grilled ginkgo nuts with salt are also a popular item at izakayas as a healthy snack with beer and other Japanese food. In Korea, ginkgo nuts are stir-fried and eaten, or are used to garnish foods such as sinseonro.

When eaten in large quantities or over a long period, the seeds may cause poisoning by ginkgotoxin (4′-O-methylpyridoxine, MPN), as found in a few case reports. A heat-stable compound not destroyed by cooking, MPN may cause convulsions, which were alleviated by treatment with pyridoxine phosphate (vitamin B6), according to limited studies.

Some people are sensitive to the chemicals in the sarcotesta, the outer fleshy coating. These people should handle the seeds with care when preparing the seeds for consumption, wearing disposable gloves. The symptoms are allergic contact dermatitis, or blisters similar to that caused by contact with poison ivy.

  • Medicinal uses

Medical research

Although extracts of Ginkgo biloba leaf are often marketed as cognitive enhancers, there is no evidence for effects on memory or attention in healthy people. Systematic reviews have shown there is no evidence for effectiveness of ginkgo in treating high blood pressure, menopause-related cognitive decline, tinnitus, post-stroke recovery, or altitude sickness. There is weak preliminary evidence for ginkgo affecting dementia and tardive dyskinesia symptoms in people with schizophrenia.

Traditional medicine

Ginkgo has been used in traditional Chinese medicine since at least the 11th century C.E. Ginkgo seeds, leaves, and nuts have traditionally been used to treat various ailments, such as dementia, asthma, bronchitis, and kidney and bladder disorders. However, there is no conclusive evidence that ginkgo is useful for any of these conditions.

The European Medicines Agency Committee on Herbal Medicinal Products concluded that medicines containing ginkgo leaf can be used for treating mild age-related dementia and mild peripheral vascular disease in adults after serious conditions have been excluded by a physician.

Ginkgo biloba (Maidenhair Tree) Details

Common name Ginkgo Maidenhair Tree
Botanical name Ginkgo biloba
Plant type Edible
Hardiness zone 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Medium
Harvest time Fall
Height 50 ft. 0 in. - 80 ft. 0 in.
Width 50 ft. 0 in. - 80 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Cream/Tan
Leaf color Green