Spec. Plant. Willd. i. 1479. Cl. 5. Ord. 2. Pentandria Digynia. Nat. ord. Anacardiaceae. G. 566. Calyx five parted. Petals five. Berry with one seed. * * With ternate leaves. Species 17. R. Toxicodendron. Poison Oak. Sumach. Kalnis

Travels, ii. 318. Officinal. Toxicodendri folia, Lond. Rhois Toxicodendri folia, Edin. Dub. Sumach leaves.

Syn. Toxicodendron, Herbe a la Puce (F.), Giftsumach (G.), Vergiftboom (Dutch), Rus Tossicodendre (I.).

This shrub is a native of North America. It seldom exceeds three feet in height; the root sending up many stems, which divide into slender, woody branches, and are covered with a brownish bark. The leaves are placed alternately, supported on long petioles; and are composed of three oval leaflets, about three inches long, and one inch and a half broad, angularly indented, hoary on the under surface, and of a deep shining green colour on the upper : the two lateral leaflets are nearly sessile, and the terminal one is considerably the largest of the three : the male flowers, which are on a distinct plan from the female, spring from the sides of the stalks in close short spikes, and are of an herbaceous colour; the female, which are larger, are produced in loose panicles, and embosom a roundish germen, supporting three very short styles: the fruit is a striated berry.

The stems, if cut or broken, exude a milky juice, which was supposed to inflame the skin wherever it touched: but this is not the case, although the plant exudes a deleterious vapour.2 The juice becomes black when it is exposed for a short time to the action of atmospheric air.8

Qualities.-The leaves of toxicodendron are inodorous, and have a mawkish, subacrid taste. Their virtues are completely extracted by water, and partially by alcohol. The aqueous infusion reddens litmus paper; precipitates the solution of sulphate of iron black; that of nitrate of silver brown; and throws down a precipitate with gelatine. Hence it contains gum, resin, gallic acid, and tannin; but a narcotic principle is also present, on which its effects principally depend.

1 'Povs Dioscoridis.

2 Vans Mons has proved that the acrimonious matter of the plant is exhaled during the night, combined with carbonated hydrogen gas. He collected a jar full of the gas, into which his brother, who was very susceptible of the poison of this species of rhus, plunging his arm, the skin was quickly inflamed and blistered. Actes de la Soc. de Med. de Bruxelles.

3 This juice forms an indelible black stain on linen cloth; and is used in Japan, where the shrub is a native, as a varnish.-Phil, Trans, xlix. 158.

Medical properties and uses.-The leaves are stimulant and narcotic. In the hands of Dr. Alderson of Hull, who introduced them as a remedy, they proved successful in several cases of paralysis, especially in paraplegia; and they have been found equally efficacious in the hands of M. Bretonneau of Tours; but we believe their efficacy in this disease has not been confirmed by the observations of other English physicians. They excite a sense of heat and pricking, and irregular twitchings in the affected limbs. We believe some advantage has been found from their use in herpetic eruptions; but this has not been very satisfactory. They have also been found useful in the form of tincture, in cramp of the stomach.

The dose of the powdered leaves may be grs. v., given twice or thrice a day, and gradually increased to Эj., in the form of a bolus.