Various odorous erect herbs approximately 30 to 90 cm (12 to 35
in.) tall, Monarda punctata has toothed leaves and large, yellow
or white flowers clustered in a few verticles surrounded by bracts.
It has petioled, lanceolate leaves narrowing at the base and a nearly
smooth corolla, yellowish with the upper lip spotted purple. The
plant grows wild in the United States and is used for the extraction
of thymol. The whole plant is used. Horsemint has a harsh, burning
aromatic flavor and a thymol-like odor.
The essential oil is obtained by distillation of the freshly cut or
partially dried herb in approximately 1% and 3% yields, respectively. The oil is a yellowish-red to brown liquid with an odor
reminiscent of thymol. Its specific gravity at 20°C is 0.930 to
0.940.
On standing, the oil deposits large crystals of thymol (44 to 61%
of the oil). Its main constituents include carvacrol, traces of limonene, and
thymol hydroquionone. Other Monarda varieties also growing in
the United States-M. fistulosa, M. didyma, and others-contain
much less thymol.
The derivative is fluid extract.
