26 AMERICAN MEDICINAL LEAVES AND HERBS. 
PENNYROYAL. 
Hedeoma pulegioides (L.) Pers. 
Pharmacopeial name.—Hedeoma. 
Other common names.—American pennyroyal, mock pennyroyal, squaw mint, tick- 
weed, stinking balm, mos- 
quito plant. 
Habitat andrange.—Pen- 
nyroyal is found in dry soil 
from Nova Scotia and 
Quebec to Dakota and 
southward. 
Description.—This very 
strongly aromatic annual 
of the mint family (Men- 
thacez) is of rather insig- 
nificant appearance, being 
a low-growing plant, about 
6 inches to a foot or so in 
height, with a slender, 
erect, much-branched and 
somewhat hairy stem. 
The opposite leaves are 
small, scarcely exceeding 
three-fourths of an inch in 
length and becoming 
smaller toward the top of 
theplant. They are borne 
on short stems and are ob- 
long ovate in shape, thin, 
blunt at the apex, nar- 
rowed at the base, and with 
margins sparingly toothed. 
The branchlets are fouran- 
gled and somewhat hairy, 
and the loose flower clus- 
ters, appearing from July to _ 
September in the axils of 
the leaves, consist of a few 
pale-bluish flowers with 2- 
hipped corolla, the erect upper one entire or slightly notched or two lobed, while the 
lower spreading lip is three cleft. (Fig. 18.) 
Collection, prices, and uses.—The leaves and flowering tops are official in the United 
States Pharmacopeceia, as is also the oil of pennyroyal distilled from them. They 
should be collected while in flower. The price paid to collectors ranges from about 
1 to 24 cents a pound. 
Pennyroyal has a strong mintlike odor and pungent taste and is used as an aromatic 
stimulant, carminative, and emmenagogue. The odor is very repulsive to insects, and 
pennyroyal is therefore much used for keeping away mosquitoes and other trouble- 
some insects. 
219 
Fic. 18.—Pennyroyal ( Hedeoma pulegioides), leaves and flowers. 
