"158 AMONG THE WILD FLOWERS. 
several have pods edged with spines ; most of 
the specimens have yellow flowers, but those of 
M. Sativa, Lucerne, are more commonly violet. | 
The two species of Oxonzs, Rest-harrow, may 
be distinguished by the comparative length of 
the pod and calyx ; the calyx is longer than the 
pod in O. arvensis, and the plant has no spines ; 
in O. Campestris, the pods exceed the calyx in 
length, and the plant is usually spinous. 
The appearance in bloom, in watery places, 
of some of the genus JWentha, Mint, suggests 
the mention of several more of the Nat. Ord. 
LazBiaT&, to which this genus belongs. 
The more common species of Jentha are, 
M., Sylvestris, Horse Mint; AZ. Satzva, Whorled 
Hairy Mint; and JZ. Arvensis, Corn Mint ; all 
of which have the flowers in whorls ; AZ. Agua- 
tica, Capitate Mint, has the flowers collected 
in terminal and axillary clusters rather than 
whorls; this is the JZ. Azrvsuta of some manuals. 
The Penny Royal of gardens is our native J. 
Pulegium. 
The more rare plants are, Spear Mint, JZ. 
viridis, of very ancient cultivation ; Peppermint, 
M. piperita, scarcely a native ; and two or three 
others. 
