HOREHOUND. 21 



leaves are opposite, petiolate, ovate or nearly round, thick, much 

 wrinkled, unequally crenate-toothed, veined, covered with pubes- 

 cence like the stem, and of a cinereous blueish-green colour ; the 

 flowers are small and disposed in dense, axillary, convex whorls, 

 subtended by setaceous villous bracteee. The calyx is tubular, 

 with ten ribs and ten narrow bristly hooked teeth, five of which 

 are alternately smaller ; the throat hairy. The corolla is nearly 

 white, bilabiate, with a cylindrical exserted tube; upper lip linear, 

 straight, cloven ; lower lip broader, three-lobed, the lateral lobes 

 acute, reflexed, the middle lobe large and somewhat emarginate. 

 The stamens are didynamous, included in the tube of the corolla, 

 tipped with small oblong anthers. The germen is four-parted, 

 surmounted by a simple filiform style and a bifid stigma. The fruit 

 consists of four oblong nuts or akenia, situated at the bottom of the 

 persistent calyx. Plate 26, fig. 2, (a) entire flower ; (6) a section 

 of the corolla ; (c) pistil ; (<:/) calyx opened to show the four nuts. 



White Horehound is rather a common plant in England, on 

 rubble and in waste places, particularly in warm dry situations ; 

 it is less frequent in Scotland and Ireland. It flowers in July and 

 August. 



The name Marrubium is said by Linnaeus to be derived from 

 Maria-Urbs, a town of Italy, situated on the borders of the 

 Fucine lake; others suppose that it comes from the Hebrew 

 Marroh, which signifies a bitter juice. It is thought to be the 

 7rpcx,(nov of Dioscorides and Theophrastus, and the Marrubium of 

 Pliny. 



Qualities. — This plant exhales a fragrant odour, which is 

 somewhat vinous or musky, agreeable at first, but soon fatiguing 

 the sense. It has a bitter, penetrating and slightly acrid flavour, 

 remaining long in the mouth. These qualities in great part 

 remain in the dried herb, but they are dissipated by long keeping. 

 Both water and alcohol extract its virtues ; the extracts have a 

 penetrating bitter taste, but the aroma is nearly all dissipated. 

 " The infusion reddens tincture of litmus, gives a deep olive-green 

 precipitate with sulphate of iron, a brown with nitrate of silver, 

 and a pale yellow with muriate of mercury : acetate and super- 

 acetate of lead do not affect it. The active principles of Horehound 

 appear therefore to be a bitter extractive, volatile oil, and gallic 

 acid."* 



Medicinal Properties and Uses. — That the White Hore- 

 * Thomson's Dispensatory, 1836, p. 436. 



