374 LABIATE 



475. HEDEOM A. AMERICAN PENNYROYAL U.S.P. VIII 



The dried leaves and tops of Hedeo'ma pulegioi'des Persoon. 



DESCRIPTION. Stem hairy; leaves % inch (12 mm.) long, short-petioled, oblong- 

 ovate, slightly serrate; flowers in small axillary cymules, with small, pale 

 blue, spotted, pubescent stamens; odor mint-like. Taste aromatic and 

 pungent. 



CONSTITUENTS. Volatile oil containing hedeomol, C 10 HigO, and pulegone, 

 CioHieO. The oil obtained from Mentha pulegium Linne" has about the same 

 specific gravity and optical rotation, and contains pulegone. 



FIG. 2 16. Hedeoma pulegioides Flowering branch. 



475 a. OLEUM HEDEOMA, U.S. VIII OIL OF PENNYROYAL 



A volatile oil distilled from the flowering plant of Hedeoma pulegioides Persoon. 



SOURCE AND DESCRIPTION. Most of the oil of pennyroyal is reported as being 



distilled in North Carolina and in the southern and eastern parts of Ohio. 



It is a pale yellow liquid, having the characteristic odor and taste of Hed- 

 eoma. Its specific gravity is 0.920 to 0.935 at 25C. It is soluble in 2 vol- 

 umes of 70 per cent, alcohol forming a solution showing not more than a 

 slightly acid reaction with litmus. 



The principal and only constituent known definitely to exist in the oil is 

 "pulegone," a ketone which can be identified by its hydrated oxime. 



