Ulmaceae
Ulmus rubra
Slippery elm · Red elm
- Part used
- bark
- Native range
- Eastern and central North America
- Morphology
- A deciduous tree to twenty metres with rough leaves and, beneath the outer bark, a fragrant inner bark that becomes mucilaginous in water.
What is in it
Evidence
Little controlled evidence. The demulcent action — mucilage coating irritated tissue — is a straightforward physical mechanism that has not needed testing to be understood.
Safety
Benign as a demulcent. Historically used to induce abortion by mechanical means, and its sale for that purpose was restricted, which is the origin of some remaining regulatory caution. Slows absorption of other drugs.
Interactions: Slows absorption of drugs taken at the same time
Regulatory: Permitted as a food and as a listed medicine ingredient.
Historical use
Used extensively by eastern North American peoples as food, as a wound dressing and for sore throat and digestive complaints. Adopted by settlers and by the Eclectics, and reportedly used as a survival food by Washington’s troops at Valley Forge.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Slippery elm belongs to the small group of entries whose action is purely physical: mucilage swells in water and coats irritated tissue. No receptor, no metabolism, nothing to absorb. That is why it has almost no trial literature and almost no controversy — the mechanism was never in doubt.
Its conservation position is unusually grim. Harvesting the inner bark means ringing the tree, which kills it, and the species is simultaneously under sustained attack from Dutch elm disease. A slow-growing tree, a fatal harvest and a fungal epidemic is not a combination a commercial market improves.
Nomenclature verified against GBIF backbone taxonomy.