628 BOTANY AND PHARMACOGNOSY. 



MARRUBIUM.— WHITE HOREHOUND.— The leaves 

 and flowering tops of Marrubium vulgare (Fam. Labiatae), a 

 perennial herb (p. 368) indigenous to Europe and Asia, and cul- 

 tivated in various parts of Europe and the United States, being 

 naturalized in waste places from Texas and Mexico to Maine 

 and Ontario.- 



Description. — Stem guadrangular, yellowish- or grayish- 

 green, 3 to 5 mm. in diameter, very pubescent ; internodes 2 to 5 

 cm. long. Leaves broadly ovate, opposite, 1.5 to 6 cm. long, 8 to 

 25 mm. broad; apex obtuse; base acute or rounded; margin 

 coarsely crenate; upper surface dark green, pubescent, veins 

 depressed, those of the first order diverging at an angle of about 

 65° and branching near the margin; under surface grayish-green, 

 very pubescent, veins prominent ; petiole 0.5 to 3 cm. long, very 

 pubescent. Flowers sessile, in axillary clusters; calyx tubular, 

 about 5 mm. long, 5- to lo-nerved, very pubescent and with 10 

 recurved, bristle-like lobes ; corolla whitish or light brown, about 7 

 mm. long, upper lip erect, entire or bifid, lower lip 3-lobed, the 

 middle lobe the largest and emarginate; stamens four, included. 

 Nutlets brownish-black, ellipsoidal, slightly compressed, about 1.5 

 mm. long, nearly smooth. Odor slight, aromatic. Taste aromatic 

 and bitter. 



Constituents. — A bitter, somewhat acrid principle marru- 

 biin, 0.02 to 4 per cent., which forms prismatic crystals and is 

 sparingly soluble in water ; several other bitter principles ; a vola- 

 tile oil ; a resin ; and tannin. 



Allied Plants. — Black horehound or M air ubiumperegrinum, 

 an herb of the old world, has ovate or lanceolate, dentate-serrate, 

 grayish, hairy leaves and flowers with straight calyx-lobes. 

 Bailota nigra (Fam. Labiatae) has cordate, rough-hairy, dark 

 green leaves, pale purple flowers and a disagreeable odor. Water 

 horehound. or Lycopus europceus has ovate-lanceolate, lobed or 

 divided leaves, the calyx lobes being triangular. 



HEDEOMA.— AMERICAN PENNYROYAL.— The leaves 

 and flowering tops of Hedeoma pulegioides (Fam. Labiatae), an 

 annual herb (Fig. 271) indigenous to the Eastern and Central 

 United States and Canada (p. 369). Pennyroyal should be col- 

 lected in July or August and dried. 



