COLLLNSONIA HORSE-BALM. 211 



Habitat. — Massachusetts to Illinois and southward. 



Parts Used. — The herb — not official. 



Constituents. — Mountain-mint has a taste intermediate between that of 

 pennyroyal and spearmint, due to its volatile oil, its only important con- 

 stituent. Virginia thyme has much less nroma, and more bitterness ; it 

 contains volatile oil, tannin, a bitter principle, etc. 



Preparations. — Used in infusion. 



Medical Properties and Uses. — The above-described species of pycnan- 

 themum, together with several others of similar properties, have been used 

 medicinally to a limited extent, for the same purposes as other labiate 

 plants are employed. As they are less agreeable than many others of the 

 order in common use, and are certainly no more efficient, they do not de- 

 mand serious attention. 



HEDEOMA.— Mock Pennyroyal. 



Hedeomapulegioides Persoon. — American Pennyroyal. 



Description. — Calyx 13-nerved, gibbous at the base, 2-lipped, the 

 throat bearded ; the upper lip 3-toothed ; the lower 2-cleft and spined. 

 Corolla 2-lipped ; the upper lip erect, flat, notched at the apex ; the lower 

 3-lobed, spreading. Stamens 2 fertile and 2 rudimentary. 



A low annual. Stem erect, 6 inches high, branching. Leaves oblong- 

 ovate, obscurely serrate, petiolate. Flowers bluish, in few-flowered, axillary 

 whorls, appearing throughout the summer. 



Habitat. — In dry fields and open woods ; everywhere common. 



Parts Used. — The leaves and tops. — United States Pharmacopooeia. 



Constituents. — Its chief and only important constituent is an aromatic 

 volatile oil. 



Reparations. — Oleum hedeomae — oil of hedeoma (oil of pennyroyal). — 

 United States Pharmacopoeia. It is often administered in infusion. 



Medical Properties and Uses. — Pennyroyal is an aromatic stimulant, 

 long used in flatulence, and to stimulate menstruation. In the latter case 

 it is not to be considered as exerting, in any sense, a specific action, but 

 simply as stimulating the secretions through its general stimulant }:>roper- 

 ties, and not through any special action upon the organs engaged in the 

 function of menstruation. 



COLLINSONI A. —Horse-Balm. 



Collinsonia Canadensis Linne. — Horse- Balm, Stone-Boot. 



Description. — Calyx 2-lipped ; the upper lip 3-toothed, the lower 2-cleft. 

 Corolla greenish-yellow, somewhat 2-lipped, the throat expanded ; the 

 upper lip nearly equally 4-lobed, the lower much larger, the margin 

 fringed. Stamens 2, rarely 4, much exserted. 



