Mentha. | LVII, LABIATE, 347 
Calyx campanulate, with short teeth . 7, M. arvensis, 
Flowering stems prostrate. Leaves small. Throat of the 
calyx closed withhairs. . . .« » .« .o -« 8 M. Pulegwum, 
1, M. silvestris, Linn. (fig. 778). Horse Mint.—Rootstock, as in 
most Mints, more or less creeping, the stems 1 to 2 feet high, erect, slightly 
branched, and, as well as the whole plant, more or less hoary with a short 
close down. Leaves closely sessile, broadly lanceolate or narrow-ovate. 
Flowers small and numerous, in dense cylindrical spikes, 1 to 2 inches long, 
usually several together, forming an oblong terminal panicle. 
In wet pastures, and waste places, along ditches, etc., in temperate and 
southern Europe and Russian and central Asia, but does not extend far 
north. In Britain, it is a doubtful native, and rare in the northern coun- 
ties. Fl. summer, rather late. 
2. M. rotundifolia, Linn. (fig. 779). Round-leaved Mint.—An erect 
perennial, like M. selvestris, but coarser, greener, and more hairy. Leaves 
broadly ovate or orbicular, much wrinkled, green above and whitish 
underneath. Spikes of flowers terminal and cylindrical, more slender than 
in the last, 1 to 2 inches or rather more in length, forming a leafy, some- 
what spreading panicle. Flowers small, pale pink, or sometimes white, 
Nearly as widely diffused over Europe and temperate Asia as the last, 
but rather more of a western plant. It spreads also more readily as an 
accompaniment of cultivation. In Britain, rather more common than JZ. 
silvestris, but, except in the southern counties, introduced, 7. summer, 
gather late. Specimens occur occasionally so nearly intermediate between 
the two species that it is difficult to say to which they belong unless seen 
growing in masses. 
3. WE. viridis, Linn. (fig. 780). Spear Mint.—An erect or ascending 
perennial, with the narrow leaves sessile or nearly so, and the cylindrical 
terminal spikes of M. silvestris, but the stem and leaves are green and 
glabrous, although there are often hairs on the calyx and bracts. 
Chiefly known in Europe, Asia, and North America, as the common 
Mint of gardens, and only found apparently wild in countries where it has 
been long cultivated. Occurs occasionally in Britain under similar cir- 
cumstances. Jl. end of summer. It is not improbably a mere variety of 
M. silvestris, of garden or accidental origin, rendered perpetual by its ready 
propagation by suckers. 
| 4, WE. piperita, Sm. (fig. 781). Pepper Mint.—A perennial, less erect 
than M. viridis, glabrous like that species or nearly so. Leaves more 
stalked and broader. Spikes fuller, consisting of larger whorls ; the lower 
ones often distant, showing an approach to the character of M. aquatica. 
The common pungent variety appears to be of garden origin, occasionally 
spreading in wet places in several parts of Europe. Indicated in several 
localities in England and Ireland. J. end of summer. It may possibly 
prove to be a mere variety of M. aquatica. 
5, M. aquatica, Linn. (fig. 782). Water Mint.—Usually a rather coarse 
perennial, 1 to 13 feet high, much branched, and almost always softly 
hairy, although some varieties become nearly glabrous. Leaves stalked, 
ovate or slightly heart-shaped. Flowers larger than in M. silvestris and 
M. rotundifolia, in dense, terminal, globular or oblong heads, of more than 
half an inch in diameter, with occasionally 1, 2, or more additional whorls 
