Common Name: Slippery Elm

General Information

Ulmus rubra is a deciduous tree with an open, spreading crown; it usually grows from 12 - 18 metres tall, occasionally reaching up to 35 metres when growing on rich, moist soils. The bole can be 60 - 90cm in diameter, exceptionally to 120cm[, , ].
The tree has a long history of medicinal use and is still commonly used in modern medicine and is an ingredient of several proprietary medications, The tree also has been used traditionally as a food and source of materials. The wood is sometimes exploited commercially, being sold with Ulmus americana as 'soft elm'[].

Known Hazards

None known

Botanical References

, ,

Range

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

Habitat

Rich deep soils, often calcareous, on the banks of streams and low rocky hillsides[, ]. Lower slopes, alluvial flood plains, stream banks, riverbanks, and wooded bottom lands; at elevations up to 600 metres, occasionally to 900 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	15.00 m
Growth Rate	Medium
Pollinators	Wind
Cultivation Status	Wild

Cultivation Details

Ulmus rubra is found in a variety of climates from the continental climate of central N. America with its cold winters and hot summers, to the subtropical regions of Florida where winters are mild. Mean annual precipitation generally increases from northwest to southeast across its range, from 530 - 2,110mm. Mean annual temperature ranges from 4° to 21°c, average Winter temperature from -15° to 12°c, and average Summer temperature from 16° - 27°c, with the length of the frost-free period ranging from 90 to 280 days[].
Prefers a position in full sun, but tolerates light shade[, ]. Grows best in a moist, fertile, well-drained loamy soil, but can adapt to most soils and drier sites[]. Plants are tolerant of urban pollution[]. Plants can tolerate periodic inundation of the soil, for up to 3 months in a year, though growth and vitality is reduced[].
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[].
Slippery elm is very susceptible to 'Dutch elm disease', a disease that has destroyed the greater part of all the native elm trees growing in countries such as Britain and USA. The disease is spread by means of beetles. Mature trees killed back by the disease will often regrow from suckers, but these too will succumb when they get larger. 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[].

Edible Uses

Leaves - raw or cooked. We have no specific information for this species, but the very young leaves of all Ulmus species can be eaten, and generally have a mild flavour[].

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[].
A tea-like beverage can be brewed from the inner bark[].

Immature fruit - raw or cooked[]. The fruit is about 20mm in diameter[].

Medicinal

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[].
The inner bark is 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[].

Other Uses

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[, , , ].
The wood is considered inferior to that of American elm (Ulmus americana) even though both are mixed and sold together as soft elm [26,35]. Slippery elm is used in the manufacture of boxes, baskets, crates, and barrels[].

Propagation

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[].