Ledum. Ledum palustre. Marsh Tea.

Ledum. Ledum palustre L. Marsh Tea. Rosmarinus Sylvestris. Marsh Cistus. Wild Rosemary. Ledon, Romarin sauvage, Fr. Porsch, Sumpfporsch, Wilder Rosmarin, G.—A small evergreen ericaceous shrub, growing in swamps and other wet places in the northern parts of Europe, Asia, and America, and in the mountainous regions of more southern latitudes. The leaves have a balsamic odor, and an aromatic, camphorous, bitter taste, and contain, among other ingredients, volatile oil and tannin. For the properties of the volatile oil, see J. P. C., 4e ser., xx, 244; also Proc. A. Ph. A., xxv, 154. It contains ledum camphor, a stearopten, together with valeric and other volatile acids, and ericinol, C₁₀H₁₆O. The tannin has been named leditannic acid, C₁₅H₂₀O₈. On boiling with dilute mineral acids it is decomposed, and ledixanthin, C₃₀H₃₄O₁₃, separates as a yellowish or reddish powder. (Thal, Ph. Z. R., 1883, 268.) Thai also extracted ericolin, C₃₄H₅₆O₂₁. This is a glucoside, which on heating with diluted sulphuric acid decomposes into sugar and ericinol, C₁₀H₁₆O, a colorless, peculiar-smelling oil, which turns brown in the air, owing to oxidation. The leaves are thought to be narcotic and diaphoretic, and have been employed in dysentery and in various cutaneous affections, particularly leprosy and scabies. In complaints of the skin they are used both internally and externally, in the form of decoction. In Germany they are sometimes substituted for hops in the preparation of beer. Ledum groenlandicum Oeder (L. latifolium Ait.), or Labrador tea, which is a larger plant than the preceding, is a native of North America, growing in damp places in Canada and the northern part of the United States. The leaves have an agreeable odor and taste, and are esteemed pectoral and tonic. They are said to have been used as a substitute for tea during the war for independence.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.