Slippery Elm
Ulmus rubra

Family: Ulmaceae

What it is like

Ulmus rubra is a deciduous Tree growing to 20 m (65ft) by 15 m (49ft) at a medium rate. See above for USDA hardiness. It is hardy to UK zone 3 and is not frost tender. It is in flower from March to May, and the seeds ripen from May to June. The species is hermaphrodite (has both male and female organs) and is pollinated by Wind. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Height (m): 20

Where it is found

Rich deep soils, often calcareous, on the banks of streams and low rocky hillsides.

Central and Southern N. America - Maine to Florida, west to Texas and North Dakota.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 2

Leaves - raw or cooked. Inner bark - raw or cooked. It can be dried, ground into a powder and then used as a thickener in soups or added to cereal flours when making bread etc. It can also be chewed as a thirst quencher. The inner bark has been cooked with fats in order to prevent them becoming rancid. Immature fruit - raw or cooked. The fruit is about 20mm in diameter. A tea-like beverage can be brewed from the inner bark.

Inner bark: the bark that is found just beneath the tough outer bark of trees and shrubs.

Tea: the various herb teas that can be used in place of tea, plus the genuine article.

Medicine

Rating: 5

Slippery elm bark is a widely used herbal remedy and is considered to be one of the most valuable of remedies in herbal practice. In particular, it is a gentle and effective remedy for irritated states of the mucous membranes of the chest, urinary tubules, stomach and intestines. The inner bark contains large quantities of a sticky slime that can be dried to a powder or made into a liquid. The inner bark is harvested in the spring from the main trunk and from larger branches, it is then dried and powdered for use as required. Ten year old bark is said to be best. Fine grades of the powder are best for internal use, coarse grades are better suited to poultices. The plant is also part of a North American formula called essiac which is a popular treatment for cancer. Its effectiveness has never been reliably proven or disproven since controlled studies have not been carried out. The other herbs included in the formula are Arctium lappa, Rumex acetosella and Rheum palmatum. The inner bark is demulcent, diuretic, emollient, expectorant, nutritive. It has a soothing and healing effect on all parts of the body that it comes into contact with and is used in the treatment of sore throats, indigestion, digestive irritation, stomach ulcers etc. It used to be frequently used as a food that was a nutritive tonic for the old, young and convalescents. It was also applied externally to fresh wounds, burns and scalds. The bark has been used as an antioxidant to prevent fats going rancid. The whole bark, including the outer bark, has been used as a mechanical irritant to abort foetuses. Its use became so widespread that it is now banned in several countries.

Demulcent: Soothes, lubricates and softens irritated tissues, especially the mucous membranes.

Diuretic: Acts on the kidneys, promoting the flow of urine.

Emollient: Softens the skin, causing warmth and moisture.

Expectorant: Clears phlegm from the chest by inducing coughing.

Nutritive: A food for convalescents to help restore strength.

Urinary: Treats urinary problems, including urinary tract infection (UTI).

Other

Rating: 3

A fibre obtained from the inner bark is used to make a twine. The boiled bark has been used for making matting, nets etc. The inner bark has been used in making baskets. The bark has been used as a roofing material. The weathered bark has been used as kindling for starting a fire. Wood - very close-grained, tough, heavy, hard, strong, durable, easy to split. It weighs 43lb per cubic foot and is used for fence posts, window sills, agricultural implements etc.

Fibre: Used for making cloth, rope, paper etc.

Kindling: Plant material that burns easily and can be used for starting fires.

Roofing: Used to give a waterproof roof to buildings. See also Thatching.

Tinder: Used for starting fires. See also Kindling.

Wood: A list of the trees and shrubs that are noted for having useful wood.

Industrial Crop: Medicinal: Most pharmaceuticals are synthesized from petroleum but 25% of modern medicines are based on plants.

Management: Coppice: Cut to the ground repeatedly - resprouting vigorously. Non-destructive management systems maintaining the soil organic carbon.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Minor Global Crop: These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.

Industrial Crop: Medicinal: Most pharmaceuticals are synthesized from petroleum but 25% of modern medicines are based on plants.

Management: Coppice: Cut to the ground repeatedly - resprouting vigorously. Non-destructive management systems maintaining the soil organic carbon.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.

Food Forest: Plants for Edible Forest Gardens and Food Forests.

How it is grown

Prefers a fertile soil in full sun, but can be grown in any soil of at least moderate quality so long as it is well drained. Plants are hardy to about -10°c. A moderately fast-growing tree, living about 200 years in the wild, but although perfectly hardy, this species does not usually thrive in Britain. Trees are often harvested in the wild for their edible inner bark, the 'slippery elm' that can be obtained from chemists and health food shops. Trees have been over-exploited in the wild, plus they have also suffered from Dutch elm disease. As a result they are becoming much less common. The slippery elm is very susceptible to 'Dutch elm disease', a disease that has destroyed the greater part of all the elm trees growing in Britain. The disease is spread by means of beetles. There is no effective cure (1992) for the problem, but most E. Asian, though not Himalayan, species are resistant (though not immune) to the disease so the potential exists to use these resistant species to develop new resistant hybrids with the native species. The various species of this genus hybridize freely with each other and pollen is easily saved, so even those species with different flowering times can be hybridized. For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. The plant growth habit is a standard with a non-suckering single trunk.

Propagating it: Seed - if sown in a cold frame as soon as it is ripe, it usually germinates within a few days. Stored seed does not germinate so well and should be sown in early spring, it requires 2 - 3 months stratification according to another report. The seed can also be harvested 'green' (when it has fully developed but before it dries on the tree) and sown immediately in a cold frame. It should germinate very quickly and will produce a larger plant by the end of the growing season. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Plants should not be allowed to grow for more than two years in a nursery bed since they form a tap root and will then move badly. Layering of suckers or coppiced shoots.

Best place to grow: Woodland Garden Canopy;

Habit: Tree

Hardiness: 3-7

Growth: Medium

Soil: Light (sandy), medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

Outer bark constituents known to cause abortions - avoid during pregnancy .

Its other names

Local names

Synonyms

U. fulva. Michx. Ulmus crispa. Willd. Ulmus pendula. Willd.

Slippery Elm Ulmus rubra