The persistent calyx encloses the ripe nutlets, and aids in their distribution in various ways, by means of winged spiny or hairy lobes or teeth; sometimes it forms a swollen bladder. A scanty endosperm is sometimes present in the seed ; the embryo is gen erally parallel to the fruit axis with a short inferior radicle and generally flat cotyledons.
The family occurs in all warm and temperate districts; its chief centre is the Mediterranean region, where some genera such as Lavandula, Thymus, Rosmarinus and others form an important feature in the vegetation. The tribe Ocimoideae is exclusively tropical and subtropical and occurs in both hemispheres. The family is well represented in Britain by nineteen native genera ; Mentha (mint) including also M. piperita (peppermint) and M. Pulegium (pennyroyal) ; Origanum vulgare (marjoram) ; Thymus Serpyllum (thyme) ; Calamintha (calamint), including also C. Clinopodium (wild basil) and C. Acinos (basil thyme) ; Salvia (sage), including S. pratensis (clary) ; Nepeta Cataria (catmint) ; N. Glechonia (ground-ivy) ; Brunella (self-heal) ; Scutellaria (skull-cap) ; Stachys (woundwort) ; S. Betonica (wood betony) ; Galeopsis (hemp-nettle) ; Lamium (dead-nettle) ; Ballota (black horehound) ; Teucrium (germander) ; and Ajuga (bugle).
Labiatae are readily distinguished from all other families of the series excepting Verbenaceae, in which, however, the style is terminal; but several genera, e.g., Ajuga, Teucrium and Rosmar inus, approach Verbenaceae in this respect, and in some genera of that order the style is more or less sunk between the ovary lobes The fruit-character indicates an affinity with Boraginaceae from which, however, they differ in habit and by characters of ovule and embryo.
The presence of volatile oil renders many genera of economic use, such as thyme, marjoram (Origanum), sage (Salvia), laven der (Lavandula), rosemary (Rosmarinus), patchouli (Pogo stemon). The tubers of Stachys Sieboldi are eaten in France.
The family is represented in North America by about 4o genera the largest being Teucrium (germander), Scutellaria (skullcap) Marrubium (horehound), Nepeta (catnip), Physostegia (dragon head), Leonurus (motherwort), Stachys (hedge nettle), Salvia (sage), Monarda (horsemint), Hedeoma (pennyroyal), Thymus (Thyme), and Mentha (mint).