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Gymnocladus dioica - (L.)K.Koch.

Common Name Kentucky Coffee Tree
Family Fabaceae or Leguminosae
USDA hardiness 3-8
Known Hazards The ripe seed contains hydrocyanic acid. This toxin can be destroyed by thoroughly heating the seed for at least 3 hours at 150°c[183]. The seed contains saponins[222]. Although toxic, these substances are very poorly absorbed by the body and so tend to pass through without causing harm. They are also broken down by heat so a long slow baking can destroy them. Saponins are found in many plants, including several that are often used for food, such as certain beans. It is not advisable to eat large quantities of food that contain saponins. Saponins are much more toxic to some creatures, such as fish, and hunting tribes have traditionally put large quantities of them in streams, lakes etc in order to stupefy or kill the fish[K].
Habitats Prefers deep rich soils in bottomlands, deep ravines and moist lower slopes[229].
Range Eastern and Central N. America - New York to Tennessee, west to Arkansas and South Dakota.
Edibility Rating    (3 of 5)
Other Uses    (3 of 5)
Weed Potential No
Medicinal Rating    (2 of 5)
Care (info)
Fully Hardy Well drained soil Moist Soil Full sun
Gymnocladus dioica Kentucky Coffee Tree

Gymnocladus dioica Kentucky Coffee Tree


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Bloom Color: White. Main Bloom Time: Early spring, Late spring, Mid spring. Form: Oval, Rounded.

Physical Characteristics

 icon of manicon of lolypop
Gymnocladus dioica is a deciduous Tree growing to 20 m (65ft) by 15 m (49ft) at a slow rate.
See above for USDA hardiness. It is hardy to UK zone 4. It is in flower in June, and the seeds ripen in October. The species is dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required). . The plant is not self-fertile.
It can fix Nitrogen.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very alkaline and saline soils.
It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought. It can tolerate atmospheric pollution.

UK Hardiness Map US Hardiness Map


G. canadensis. Guilandina dioica.

Plant Habitats

Woodland Garden Canopy; Secondary;

Edible Uses

Edible Parts: Seed  Seedpod
Edible Uses: Coffee

Seedpod - raw or cooked. The roasted seeds can be eaten like sweet chestnuts[257]. The pulp is sweet[2, 82]. A flavour like caramel[222]. The pods are up to 25cm long and 5cm wide[229]. The roasted seed is a caffeine-free coffee substitute[2, 11, 46, 95, 213]. A bitter flavour[226]. Thorough roasting for at least 3 hours at 150°c is necessary in order to destroy the poisonous hydrocyanic acid that is found in the seed[183]. Seed - roasted and eaten like a nut[161, 213, 226]. The seed contains toxic substances, see notes above.

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Homeopathy  Miscellany

The pulverised root bark is used as an effective enema[213, 222, 257]. A tea made from the bark is diuretic[222]. It is used in the treatment of coughs due to inflamed mucous membranes and also to help speed up a protracted labour[222]. A snuff made from the pulverized root bark has been used to cause sneezing in comatose patients[257]. A tea made from the leaves and pulp from the pods is laxative and has also been used in the treatment of reflex troubles[222]. A decoction of the fresh green pulp of the unripe fruit is used in homeopathic practice[82].

References   More on Medicinal Uses

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Other Uses

Insecticide  Miscellany  Soap  Soil reclamation  Wood

The fruit is high in saponins and is used as a soap[200]. The leaves are used as a fly poison[222]. Trees are planted on the spoil tips of mines to stabilize and reclaim the soil[200]. Wood - coarse-grained, heavy though not hard, strong, very durable in contact with the soil, finishes to a fine lustre. A handsome wood, it weighs 43lb per cubic foot and is used for cabinet work, furniture, construction, fencing etc[46, 61, 82, 171, 229, 235].

Special Uses

Nitrogen Fixer

References   More on Other Uses

Cultivation details

Landscape Uses:Pest tolerant, Specimen, Street tree. Requires a deep rich soil and a sunny position[1, 200]. Tolerates drought, atmospheric pollution, salt and limestone soils[200]. A very cold-hardy plant, tolerating temperatures down to about -30°c[200]. A very ornamental[1] but slow growing tree[11], it rarely flowers in Britain, requiring more summer heat than it usually gets here[11, 200]. Trees in the wild seldom live longer than 100 years[229]. The tree has a light canopy so does not cast much shade[200], making it a good tree to use for the top canopy of a woodland garden. Dioecious. Male and female plants must be grown if seed is required. Unlike most members of the Leguminosae, his species does not form nodules of nitrogen-producing bacteria on the roots[274]. Special Features: North American native, Fragrant flowers, Inconspicuous flowers or blooms.

References   Carbon Farming Information and Carbon Sequestration Information

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Plant Propagation

Seed - best sown in a greenhouse as soon as it is ripe[200]. The seed can also be sown in early spring in a greenhouse[78]. Scarification and pre-soaking the seed for 24 hours in warm water, especially if it has been stored, will improve germination[200]. Make sure the seed has swollen after soaking, soak it again if it has not and, if it still does not swell, try filing away some of the seedcoat but be careful not to damage the embryo. As soon as they are large enough to handle, prick the seedlings out into fairly deep individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Consider giving them some protection against the cold for their first couple of winters outdoors Root cuttings 4cm long and 1cm thick in a greenhouse in December[200]. Plant the roots horizontally in pots[78]. Good percentage.

Other Names

If available other names are mentioned here

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Gymnocladus chinensisSoap TreeTree12.0 8-11 SLMHNM202

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.


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Readers comment

Rodrigo   Sat Jan 14 2006

Ilike what I read, But we have the kentucky coffee tree in southwest Idaho, i think your range should include the northwest states. we have had our trees for six years and they took like fish to water.

Lew Ward   Sat Jan 14 2006

The reange of plants in most Flora's is refering to the known natural range. Plants when introduced outside the natural range will often thrive.

MARCUS THORNTON   Wed Feb 7 2007


Ken Fern, Plants for a Future   Wed Feb 21 2007

A great many plants have various anti-nutritive factors in them in an attempt to stop themselves being eaten by plant eaters. Generally, the plant eater will find leaves that are toxic to itself to be unpalatable - a necessary ability otherwise all the plant eaters will be killed off by the plants. A lot of plant eaters restrict their diet to just one, or a small number of species that they have evolved to eat. Where species eat a very varied plant diet they are either taught by their mother which plant foods are safe to eat, or they have a system of trying very small quantities of a novel food in order to see if it has any negative effects. It is also a fact that plants are not universally poisonous. Many animal species have evolved to be able to safely deal with toxins that would kill another creature. There can occasionally be problems when an exotic poisonous species is introduced into a new area - but the main animal species that is likely to be poisoned is the Human one - we do seem to have lost touch so much with nature that we are nowhere near as aware as other species about the negative effects of some foods we eat.

Little Bit Farm   Mon Nov 17 2008

All I want to know is who got the brilliant idea to make comatose patients sneeze? I mean, there you are on death's doorstep, and some brilliant person decodes to stick stuff up your nose to see if you will sneeze? Thank you very much!

Johann   Sat Aug 22 2009

This article leaves it open whether the tree fixes nitrogen or not. In one part of the article it is said to do so, while in another part of the article is said not do so. Can somebody put light on this? Thank you.

Zack   Tue Oct 27 2009

According to the USDA this is not a nitrogen fixing plant, despite being a member of the Fabaceae family.


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