Labiatae

views updated

Labiatae A family of herbs or low shrubs, comprising a natural group, whose members have quadrangular stems and simple leaves without stipules in opposite pairs. Commonly there are apparently whorled spikes of flowers; actually branched cymes are borne in the axils of opposite pairs of bracts but are usually very condensed. The flowers are strongly irregular, with a 5-toothed or 2-lipped calyx and a tubular corolla which is often clearly 2-lipped but may have only the lower lip developed. There are 2 or 4 stamens and a 4-lobed ovary with the style inserted between the 4 lobes. The fruit is composed of 4, separating, 1-seeded nutlets, a clear distinction from those genera of Scrophulariaceae which are superficially similar. Many genera and species (e.g. mints and sages) are used as flavourings, as they contain aromatic, volatile, essential oils. Some of these oils (e.g. menthol and thymol) are used as mild antiseptics. Many species are cultivated for their flowers, others beautify northern temperate woodlands in springtime. There are 224 genera, with about 5600 species, and their main distribution is in tropical and warmer temperate regions.