This section is from the book "Sub-Alpine Plants Or Flowers Of The Swiss Woods And Meadows", by H. Stuart Thompson. Also available from Amazon: Sub-Alpine Plants: Or, Flowers of the Swiss Woods and Meadows.
Herbs, or rarely shrubs, with square stems and opposite leaves, often glandular and fragrant. Flowers solitary, or in opposite, axillary, crowded, stalked, or sessile cymes. Corolla tubular and 2-lipped. Calyx persistent, 5-cleft. Stamens 4, epipetalous, rarely 2. Ovary 4-lobed, with one ovule in each lobe. Stigma 2-fid. Fruit of four 1-seeded nutlets.
A very large family, spread all over the globe, and easily known from all other Monopetals, except the Borage family, by the 4-lobed ovary and the 4 small nuts in the base of the calyx. The family, however, comprises comparatively few Alpine species, and not one high "Alpine".
Flowers small, in dense axillary cymes or leafy spikes. Corolla-tube short, limb 4-lobed. Stamens nearly equal; whole plant usually strongly scented.
About 30 species inhabiting north temperate regions. They hybridise very easily, and hence are rather difficult to determine. The Swiss Mints are practically the same as the English.
Stems 2-3 feet high, erect, slightly branched, hoary like the whole plant with close down. Leaves sessile, broadly lanceolate. Flowers small and numerous, in dense cylindrical spikes, forming oblong-terminal panicles.
Wet mountain pastures and waste places in the plains, forming great colonies in some sub-Alpine districts as, e.g. about Argentiere.
Temperate and Southern Europe, Russian and Central Asia. British.
Flowers small, in axillary cymes, often unisexual. Calyx 2-lipped. Corolla obscurely 2-lipped. Stamens 4, very unequal. Leaves small, entire. Stem procumbent. Most species very fragrant.
Stems slender, prostrate, much branched, hard but scarcely woody at the base, forming low, dense tufts, and often almost covered with purple flowers. Leaves very small, oblong or ovate, fringed with a few long hairs at the base. Flowers usually 6 in a whorl, with no true bracts, in short, terminal, leafy spikes. Calyx usually hairy, and whole plant often densely covered with short, hoary hairs. Very polymorphic, and in Switzerland several subspecies and varieties are known.
Banks, hillsides, and pastures from the plains to 9000 feet.
Europe, Northern and Central Asia. British.
Flowers usually in whorls of 6 or more, forming terminal racemes or spikes. Calyx 2-lipped, the upper lip entire or with 3 small teeth, the lower one 2-cleft. Corolla with upper lip erect, concave or arched, the lower spreading, 3-lobed, the middle lobe often notched. Stamens really 2, but easily mistaken for 4, on account of the arrangement of the anthers, which have a long, slender convectivum having the appearance of a filament.
A large genus widely spread over temperate and warm regions of the globe, being mountain plants within the tropics.