102 
Petals nearly equal in length; fruit, or ‘ pod,” irregularly. 
wrinkled, shortly hairy. | 
officina'lis.7 
The innermost petal, or “keel,” shorter than the rest; 
pod transversely wrinkled, not hairy. ; } 
arvensis. 
MEN’THA. 
Stem ending in one or more clusters of flowers. 
_Leaves not (or very indistinctly) stalked. 
| _-Leaves green on both surfaces, almost or quite 
[ without hairs. viridis. Spear Mint. 
Leaves whitish and hairy on their lower surface. 
Leaves short and wide, obtuse, much wrinkled on 
f their upper surface. | 
' rotundifollia,~ 
Leaves pointed, usually narrower, not wrinkled on 
their upper surface. , 
L sylvestris. Horse M int 
Leaves distinctly stalked. 
Flowers in an elongated spike or cluster at the end 
{ of the stem. } 
( piperita. Peppermint. 
Flowers collected into a roundish mass at the end of 
the stem. j 
q aquatica. Water Mint. 
Stem terminating in a pair or tuft of leaves, either not 
enclosing flowers, or, if so, projecting beyond | 
them. 
Leaves an inch or more; calyx-teeth nearly equal. 
Calyx oblong, little dilated, with narrow teeth. " 
Calyx wide, its teeth as wide as they are long. 
L arven'sis. Corn Mint.) 
Leaves about half an inch long; the 2 lower calyx- 
teeth longer and narrower than the others. 
Pule’'gium /Pennyroyal. 
MERCURIA'LIS. 
Leaves rough and harsh to the touch, the lowest ones 
small ; stem unbranched. 
A sati'va. Whorled Mint.) 
=) 
peren'nis. Log’s Mercury. 
I.eaves smooth, the lowest ones scarcely shorter than 
those above; stem usually branched. 
annua. Annual Mercury. 
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