Simply stated, female ginkgos stink. This is not a sexist remark if you’re addressing a dioecious tree — simplified, a tree that grows either male or female flowers on separate plants. The male ginkgo bears no fruit, but those of the female are uniquely malodorous. They have been likened to vegetal vomit (the acrid scent attributable to butyric acid in the soft outer parts of the fruit), and though hard to appreciate, it imparts some adaptive value to the ginkgo fruit — attracting or discouraging interest.
Near the corner of Avenue U and 23rd Street, not far from where I grew up in Brooklyn, a female ginkgo tree was planted where a male tree was undoubtedly intended. The sheer abundance of this tree’s fruits each autumn required herculean feats just to walk past. Holding my breath, I’d sprint by the tree and the dozens of rank yellow fruits that lay like stink bombs all around it. My first encounter with the ginkgo was while running an errand to my parent’s preferred Chinese laundry, located around the corner. Having passed the stench, I opened the shop’s door only to find an overflowing bag of the horrid little fruits on the counter — the owner still beaming with delight at this locavore bumper crop.
It was years later that I discovered the tree was a ginkgo (Ginkgo biloba), a species that is the sole living descendant of an ancient lineage. When dinosaurs roamed the earth, trees very like the modern ginkgo provided them food and cover.
Consequently, the plants have some very odd attributes, including one particularly vivid reproductive strategy. Like cycads — their gymnosperm relatives — and ferns, the ginkgo produces motile sperm. This is not metaphoric sperm: This very stationary tree produces a wriggling, swimming sperm cell capable of fertilizing female ginkgo ovules.
- It’s Stinking Ginkgo Time!
- Ginkgo Male Vs. Female: Telling Male And Female Ginkgoes Apart
- How to Tell Ginkgo Sex Between Trees
- Growing ginkgo from seed
- Ginkgo or Maidenhair Tree
- Mature Height/Spread
- Growth Rate
- Ornamental Features
- Landscape Use
- SelecTree: Tree Detail
- It’s stinky tree season! Smell of Ginko nuts invade Sacramento
It’s Stinking Ginkgo Time!
Posted in Gardens and Collections, Science on October 21 2008, by Plant Talk
|Karen Daubmann is Director of Exhibitions and Seasonal Displays.|
If you’re walking or driving along the perimeter of the Botanical Garden on Kazimiroff Boulevard, you might be detecting a pungent, foul odor in the air. You might also be seeing people collect what seems to be the source of that smell.
It is the time of year that female ginkgo trees drop their fleshy fruit, which when crushed by passing cars or pedestrians release a stench that has been likened to rotten butter, vomit, or dog excrement. It is what gives the ginkgo tree a bad name.
Though they smell terrible, the female cones, once harvested and processed, reveal seeds known as “white nuts” or “ginkgo nuts.” These seeds are a delicacy in Chinese and Japanese cooking, used in stuffing, soups, and even desserts. This treat is also nutritious, containing 13% protein and 3% fats. That is why female ginkgo trees are sought out at this time of year by those who envision making Bird’s Nest Soup and other traditional Asian dishes. Ginkgo seed hunters carry gloves and Ziploc bags while wearing shoes with soles that can be easily washed.
Are you familiar with the ginkgo tree? These stately trees—mature trees can reach 100 feet tall—have light-gray bark and fan-shaped leaves. As they age, the crown of the tree gets wider, and in autumn its turn golden yellow. Ginkgo, or maidenhair tree, is known as a “living fossil,” because it was a common tree species when dinosaurs roamed Earth, about 225 million years ago. Ginkgo was thought to be extinct until several plantings were discovered in eastern China.
Learn why the ginkgo tree is unique after the jump.
Ginkgo is an unusual tree for a number of reasons.
â€¢ Ginkgo is considered a conifer but unlike typical conifers (pine, spruce, fir) it does not have needles. Its leaves fall to the ground each autumn.
â€¢ Ginkgo is a monotypic species, meaning that the family Ginkgoaceae contains only one plant, Ginkgo biloba. Families like Aceraceae (maples) contain over 100 species.
â€¢ Ginkgo is dioecious, meaning that each tree has its own sex, either male or female. The sex can’t be determined until the tree reaches fruiting age, which takes nearly 20 years. Modern cultivars, including ‘Autumn Gold’ have been created through grafting, which splices cuttings from male ginkgo trees onto ginkgo rootstock grown from seed.
â€¢ Ginkgo biloba leaves are harvested, made into pills, and sold as an herbal remedy for improving long- and short-term memory.
Because of the ginkgo’s graceful leaves, gorgeous fall color, hardiness, and ability to endure pollution, it is a worthy and popular choice as a street tree—that is, the male ginkgo, which doesn’t bear fruit.
According to the City of New York Parks and Recreation Department’s 2006 Trees Count! street tree survey, there are nearly 16,580 Ginkgo biloba planted as street trees within city limits. That means that at this time of year, while enjoying the golden fall color of ginkgos, be careful where you step!
Ginkgo Male Vs. Female: Telling Male And Female Ginkgoes Apart
Ginkgo biloba is a strong, long-lived specimen with many uses here in the U.S. It grows as a street tree, on commercial properties, and in the home landscape of many. Sources say it is near perfect as an urban tree goes, as it can grow and thrive in pollution, resists disease, and is easy to prune. But one thing that’s not so near perfect is its sex.
How to Tell Ginkgo Sex Between Trees
The gingko is a beautiful tree, growing in a diversity of climates. It is the only surviving specimen of the division Ginkgophyta that has not become extinct. There are many instances of prehistoric fossils of this tree being found, some dating as far back as 270 million years. Fossils were found on all continents with the exception of Antarctica and Australia. Needless to say, it’s been around awhile.
You may ask, are ginkgoes dioecious? They are, with both male and female plants. Female plants are the source of the only complaint lodged against this tree, with smelly fruit that drops in autumn. In fact, some street cleaning crews in areas where the trees grow in mass are assigned to pick up the fruit as it drops.
Unfortunately, the growth and dropping of the fruit is also about the only way to tell a ginkgo male vs. female. Described as an offensive, long-lasting smell, the edible fruit a definitive way to determine the sex of this tree. And if your goal is to avoid the foul-smelling, untidy fruit, then you may be wondering about other methods of telling male and female ginkgoes apart.
Flowers in bloom can also give some indication of sex, as the female flower has a single pistil. These trees bear seeds within cones, comprised of seeds on the inside. The outer covering, called sarcotesta, is what emits the stinky smell.
Learning how to tell ginkgo sex has been a course of study for arborists, scientists, and horticulturists alike. The presence of this covered seed is the only way to tell male and female ginkgo differences. A few ‘male only’ cultivars are in development, but this is not foolproof either, as it is proven that the ginkgo trees can change sexes. So even if there is a way of telling male and female ginkgoes apart, that doesn’t mean the sex of the tree is permanent.
Many states in the U.S. and cities in other countries continue to plant ginkgo trees. Obviously, the ease of their growth and inexpensive maintenance overrides the smell of the autumn season. If you wish to find a male ginkgo for planting, keep an eye on cultivar development. New varieties are on the horizon.
Growing ginkgo from seed
Ginkgo biloba produces neither seeds nor fruit. Male trees bear pollen and female trees, ovules, commonly called “fruit.”
A mature ovule resembles a small golden plum. Beneath the fleshy outer layer there is a woody shell that looks like a large pistachio. This “seed” contains an almond-like “nut” (see the box below).
Gather the ovules when they fall to the ground in late October or early November. It is important to wear gloves when handling the ovules, because contact with the fleshy layer can cause dermatitis. This “pulp” is also toxic if ingested. Note that the pulp gives off an odour of rancid butter or vomit as it decays.
Soak the ovules in water to remove the fleshy layer. To allow the embryo to completely mature, you will need to warm stratify the “nuts” for 6 to 8 weeks, and then cold stratify them for the same length of time or even all winter. After this artificial stratification period, you can pot them up. The containers can be placed outdoors once temperatures are warm enough in spring. Alternatively, you can sow your ginkgo “nuts” in the fall directly in the ground or in containers buried in the soil, to stratify them naturally. Only fertilized ovules will germinate.
Artificial stratification is intended to reproduce the natural conditions the seeds need in order to germinate. An easy way to stratify ginkgo “nuts” artificially is to mix them with moist sand, vermiculite or peat moss in clear plastic bags with small holes punched in the sides. For warm stratification, keep the bag at 20 to30°C. Check the medium periodically to make sure that it doesn’t dry out. A refrigerator (at about5°C) is ideal for cold stratification.
An almond or pit is the seed of a peach, plum, apricot and other drupe or stone fruit. A ginkgo “almond” or “nut” is actually the endosperm or female prothallium (nutrient-storage tissue). It is eaten inAsia, despite being potentially toxic. Cooking is said to destroy the toxin (ginkgotoxin), but the cooked “nuts” should still be eaten in moderation. A number of cases of poisoning have been reported, with children being most vulnerable.
Ginkgo or Maidenhair Tree
Ginkgo biloba, or maidenhair tree, is an ancient “living fossil” that is considered one of the oldest plants on earth. Based on fossil evidence, it has remained essentially unchanged since its debut 180 million years ago during the lower Jurassic period. For centuries gingko has been cultivated in China, Japan and Korea, where trees exceed 100 feet in height and live up to 1,000 years.
Distinctive fan-shaped leaves of Ginkgo biloba. Note the fruit on this female tree.
Bob Polomski, ©2014, Clemson Extension.
Ginkgo arrived in North America in 1784 (Philadelphia, PA) via England. In 1841 nurseryman and horticulturist Andrew Jackson Downing promoted ginkgo’s ornamental merits and importance as a landscape tree:
“As the foliage is of that kind which must be viewed nearby, to understand its peculiarity, and as the form and outline of the tree are pleasing, and harmonizes well with buildings, we would recommend that it be planted near the house where its unique character can be readily seen and appreciated.”
Gingko is cold hardy in USDA zones 4 to 8b. It is a large, deciduous shade tree (although dwarf cultivars exist), and is somewhat slow-growing. Although closely related to conifers, it has no resemblance to needle-leaved species. Gingko possesses 2- to 3-inch long and wide, emerald-green, fan-shaped leaves with rounded lobes (hence the name “biloba”). They resemble the leaflets of maidenhair fern (Adiantum spp.), which give it its common name. In the fall the leaves turn brilliant golden yellow and then all at once are shed to create a golden carpet beneath the tree.
Its “cones” are 1- to 2-inch long, orange or yellow plum-like fruits with edible fleshy seeds. Only female trees bear (pistillate) flowers that give rise to attractive “fruits”, technically ovules, which ripen to produce fleshy-coated seeds in the fall. Eventually they also become malodorous and messy when they are shed from the tree and decompose. Male gingko trees produce staminate flowers, and male cultivars tend to be more numerous than females because of their absence of fruit.
Ginkgo biloba on the Clemson Univ. campus.
Bob Polomski ©2014, Clemson Extension
Young ginkgo trees tend to look gangly and stark with irregularly shaped, open canopies. However, they become more picturesque with age as they grow 50 to 80 feet high and 30 to 40 feet wide and develop full, round to pyramidal crowns.
Ginkgo grows slowly in its youth, but more moderately as it matures in full sun to partial shade. Supplemental watering during the summer months during dry spells and periodic fertilization in mid-spring and/or early fall will encourage growth. For more information on fertilizing and irrigating trees, refer to HGIC 1000, Fertilizing Tree & Shrubs and HGIC 1056, Watering Shrubs & Trees.
The unusual, emerald fan-shaped leaves contribute to gingko’s allure in the landscape. When these leaves turn vibrant yellow in fall—one of the earliest to turn color in the fall—you can appreciate an extended colorful display that ends at one time when nearly all of the leaves are shed at once, which makes cleanup a one-time chore.
Dormant, mature gingko trees showcase an attractive winter silhouette with light gray furrowed bark and prickly-looking branches that bear spurs along their length. These shortened shoots bear male or female flowers and offer textural winter interest.
Brilliant, golden fall color of Ginkgo biloba.
Joey Williamson, ©2014 HGIC, Clemson Extension
The shortened shoots called spurs support male or female flowers and offer winter interest.
Karen Russ, ©2014 HGIC, Clemson Extension
Ginkgo combines urban toughness with beauty. They are widely planted along streets and in parking lots, parks and golf courses. For residential landscapes, consider smaller stature gingko cultivars to serve as specimen or accent trees (see Cultivars section).
Gingko is not difficult to transplant, but fall and winter planting favors establishment. Choose a well-drained location in full sun to partial shade. Once established, gingko exhibits moderate heat and drought tolerance. For more information on planting trees, refer to HGIC 1001, Planting Trees Correctly.
Young trees require structural or formative pruning by cutting back any wayward branches and any competing vertical limbs to maintain a central leader. Occasionally the understock of a grafted cultivar will produce suckers that have to be removed. After its young formative years, mature trees require little pruning except to remove dead, broken, or weak limbs. For more information on pruning, refer to HGIC 1003, Pruning Trees.
Ginkgo is relatively free of pests, and tolerant of salt and air pollution. Ginkgo has proven to be an outstanding landscape and street tree, and with proper siting, planting and pruning, it can be expected to prosper.
As a street tree, there are reports of abiotic leaf scorch due to high heat and drought stress that have been reported. Ginkgo is also susceptible to bacterial leaf scorch caused by the bacterium Xylella fastidiosa, which often infects stressed trees. This bacterium is vectored by leafhopper and treehopper insects. The symptoms of both types of leaf scorch look similar and often require a laboratory analysis to determine the causal factor.
Abiotic leaf scorch can generally be relieved by proper irrigation. However, bacterial leaf scorch is incurable and can lead to decline and often the death of infected trees. Because ginkgo is susceptible to bacterial leaf scorch disease, it is not recommended as a replacement tree in situations where other trees have succumbed to this disease.
As stated earlier, female trees can become a nuisance when they reach reproductive maturity (20 years or more) and bear fruit. Their unpleasant smelling and messy fruits are shed from the tree in the fall months and decompose. To prevent this problem, it is best to select male cultivars rather than seed-propagated trees which will not reveal their gender until they have become well-established in your landscape.
The ginkgo kernel is considered a delicacy in China & Japan.
Bob Polomski, ©2014, Clemson Extension.
A large number of gingko cultivars—most often males—have been introduced to the marketplace. They range in size from dwarf to large trees, narrow and upright to broad and wide-spreading forms. Other cultivars have variegated leaves or a weeping, pendulous habit. Cultivars that have been selected from witch’s brooms (‘Jehoshaphat’, ‘Munchkin’, and ‘Troll’) have become collector’s items and conversation pieces because of their bizarre-looking leaves and bushy compact habit. The following ginkgo cultivars comprise a short list of desirable trees that merit planting in South Carolina landscapes.
- ‘Autumn Gold’ ̶ A male selected for bright golden yellow fall color; matures to a respective height and spread of 50 feet and 30 feet, and develops a broadly conical, symmetrical crown.
- ‘Chase Manhattan’ (‘Bon’s Dwarf’) – A shrubby, very slow-growing dwarf cultivar with smaller leaves than the species and develops a compact growth habit with an expected height of 6 feet at maturity. Bright yellow fall color.
- ‘Fairmount’ – A male clone propagated in 1876 from a male tree planted during the Centennial Exposition in Philadelphia, Penn., at Horticultural Hall in Fairmount Park. It matures into a dense, columnar crowned tree, 50 to 75 feet high by 10 to 15 feet wide.
- Gold Colonnade® (‘JFS-UGA2’) ̶ This upright cultivar with a narrow oval canopy is expected to grow 45 feet tall by 25 feet wide with bright gold fall color. A Univ. of Georgia selection.
- ‘Golden Globe’ – A reportedly a fast-grower, this male tends to produce a full dense crown when young, quite unlike typical immature gingko, and eventually develops a broad round crown with bright yellow fall color.
- ‘King of Dongting Mountain’ (‘King of Dongtingshan Mountain’) – A female cultivar that produces the largest seeds, which are considered a culinary delicacy in Asian cultures. A 500 year old tree measured 52 feet high.
- ‘Magyar’ ̶ A male columnar form that matures at 60 feet high and half as wide with uniform, symmetrical branching habit and a narrow, upright pyramidal form.
- Princeton Sentry® (‘PNI 2720’) ̶ An upright, narrow growing male with an expected height of 60 feet and a spread of 25 feet that sports a dense crown.
Princeton Sentry® ginkgo in winter.
Karen Russ, ©2014 HGIC, Clemson Extension
- ‘Majestic Butterfly’ – A variegated ginkgo having green leaves streaked with yellow. It maintains the variegation over the entire growing season. Site this cultivar in afternoon shade. Expect a mature height of 10 feet. Discovered as a sport on G. biloba ‘Jade Butterflies’.
- ‘Shangri-la’ ̶ A fast-growing male that forms a compact, pyramidal shape with dense canopy and smaller height than the species. Reaches a mature height of 40 feet.
SelecTree: Tree Detail
Resistant to oak root fungus. Smog tolerant. Female tree has fruit with obnoxious odor. Plant male trees to avoid fruit. Can grow to 100 feet in the right conditions but commonly shorter.
Has Unpleasant Fruit fragrance.
Native to China.
Trees may be referred to as male or female.
A Ginkgo biloba in Sacramento Capital Park #223 is registered as a California Big Tree. It measures 84 feet high, with a trunk circumference of 188 inches and a crown spread of 77 feet.
Erect or Spreading and requires ample growing space.
Has Deciduous foliage.
Height: 35 – 65 feet.
Width: 25 feet.
Growth Rate: 12 to 24 Inches per Year.
Longevity Greater than 150 years.
Leaves Rhomboidal, Medium to Light Green, Gold, Deciduous.
Flowers Inconspicuous. Flowers in Spring. Has either male or female flowers (dioecious). Trees may be sold as male or female.
Orange or Yellow Drupe, Medium (0.50 – 1.50 inches), fruiting in Fall.
Bark Light Green, Fissured.
Shading Capacity Rated as Moderate in Leaf.
Shading Capacity Rated as Moderately Low out of Leaf.
Litter Issue is Wet Fruit.
It’s stinky tree season! Smell of Ginko nuts invade Sacramento
There’s a pungent smell making its way through Sacramento, and chances are it’s caused your nostrils to flair.
Some say it smells like dog poop, others say vomit. But the odor comes from fruit on a tree commonly found all over the Valley. It’s called the Ginkgo Biloba.
In October, Norma Westwick’s Ginko tree drops a full garbage can full of the smelly fruit on her yard.
“It’s a beautiful tree but it a lot of work.” Westwick said. “They fall on the sidewalk and when people step on them… That’s when you smell it.”
The fruit is a nuisance to Westwick, but every year she gets help cleaning up the fruit.
“A lot of times, people from the older Asian population pick them up by the bucket.” Westwick said.
The nut inside the stinky fruit is a delicious in many Asian cultures and are known to have various health benefits. Removing the smell from the nuts requires some work and there are several ways to cook them.
If you don’t want to do the dirty work you can find prepared nuts at most Asian markets.
The trees also have historic roots in China, according Sacramento Tree Foundation arborist Pamela Sanchez.
“These trees are very similar in form to what has been around since the time of the dinosaurs.” Sanchez said.
The Ginko tree is one tough tree and they do really will in urban or polluted areas. That’s why the SMUD and Sacramento Tree Foundation encourage home owners to plant them.
“Most people chose to plant the male tree instead of the female tree, which has fruit.” Sanchez said, noting that sometimes that doesn’t help. There is proof that Ginkgo trees sometimes change sex for unknown reasons. “They really are a wonderful tree and the smell only lasts a short while.”
The Sacramento Tree Foundation offer free trees and advice. Go to their website for details: www.sactree.com
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