Ulmaceae

Ulmus rubra

Slippery elm · Red elm

Untested Low Under pressure from Dutch elm disease and from bark harvesting

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

mucilage

tannins

starch

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.

What it is taken for, and who says so

Sold as a powder or lozenge for sore throat, reflux and gut irritation, and it is a staple of gut-healing protocols.

Recorded because it is what people believe, not because it is what the plant does. Whether any of it holds up is the Evidence section above, and the two frequently disagree. A sincere account of feeling better is compatible with the plant doing nothing — see the placebo effect.

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.