Lamiaceae Martinov

Scientific Description

Common name. Mint Family.

Habit and leaf form. Herbs (usually), or shrubs (sometimes ericoid), or trees (rarely), or lianas (rarely); characteristically bearing essential oils (the crushed foliage aromatic or foetid, with taxonomic predictability). Plants unarmed (usually), or spiny. The herbs annual to perennial; plants with neither basal nor terminal concentrations of leaves. Young stems usually tetragonal. Stem internodes solid, or hollow. Self supporting (usually), or climbing (occasionally). Helophytic, or mesophytic, or xerophytic. Leaves opposite (decussate on the usually square stem), or whorled; when whorled, 3–10 per whorl (e.g. Dysophylla); petiolate to sessile; aromatic, or foetid, or without marked odour (very rarely); simple, or compound; epulvinate; when compound, pinnate. Leaf blades dissected, or entire; flat, or folded, or rolled, or solid; when dissected, pinnatifid, or palmately lobed; one-veined, or pinnately veined, or pinnately veined to palmately veined; cross-venulate; cordate to cuneate at the base, or rounded at the base. Leaves without stipules. Leaf blade margins entire, or crenate, or serrate. Leaves without a persistent basal meristem. Domatia recorded (Cuminia); represented by pockets. Leaf anatomy. Hydathodes present (occasionally), or absent. Glandular hairs present (usually conspicuous). Urticating hairs absent. Stem anatomy. Nodes unilacunar (with 1 or 2 traces). Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male, or functionally female, or hermaphrodite, functionally male, and functionally female. Unisexual flowers present, or absent. Plants hermaphrodite, or dioecious, or gynodioecious (fairly commonly), or polygamomonoecious (rarely). Entomophilous, or ornithophilous; usually via hymenoptera, or via lepidoptera, or via diptera.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; in verticils (usually, these usually formed from axillary pairs of dichasial or circinate cymes), or in heads, or in spikes, or in cymes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary. Flowers minute to medium-sized; somewhat irregular to very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium (though sometimes not the calyx). Flowers cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk often present, or absent. Perianth with distinct calyx and corolla; 4–10 (theoretically 10, but variously disguised); 2 -whorled; isomerous, or anisomerous (or only dubiously interpretable). Calyx 2, or 3, or 4, or 5 (typically 5, but 2-lobed in e.g. Prostanthera, 3-lobed in Melittis, 4-lobed in e.g. Preslia); 1 -whorled; variously gamosepalous; entire (occasionally), or lobed; usually blunt-lobed, or toothed; imbricate, or open in bud (commonly); campanulate, or funnel-shaped, or tubular; unequal but not bilabiate (one-lipped), or bilabiate, or regular; persistent; (when K 5) with the median member posterior. Corolla more or less disguisedly 5 (usually with no clear indication of individual petals — commonly with five lobes, but usually with the bilabiate condition superimposed, and the five lobes variously secondarily lobed, reduced or suppressed), or 4 (sometimes, ostensibly, e.g. Mentha, Pogostemon); 1 -whorled; gamopetalous; imbricate; bilabiate (usually, the lower lip typically three-lobed, the upper commonly bilobed or emarginate but sometimes entire or three or four lobed), or unequal but not bilabiate (e.g. Teucrium, where the upper lip is suppressed), or regular to unequal but not bilabiate (rarely almost regular as in Mentha); plain, or with contrasting markings. Fertile stamens usually present, or absent (in female flowers). Androecium 2, or 4(–5) (usually). Androecial members adnate; markedly unequal (usually), or all equal; usually free of one another, or coherent (in Coleus); in Coleus 1 - adelphous; 1 -whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, 1 (posterior), or 2 (the posterior pair, or the anterior pair); representing the posterior median member, or the posterior-lateral pair, or the anterior-lateral pair. Stamens 2, or 4, or 8–10 (very rarely). Staminal insertion near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube. Stamens didynamous (usually, with the anterior pair longer), or not didynamous, not tetradynamous; usually reduced in number relative to the adjacent perianth (at least theoretically); fertile stamens representing the posterior-lateral pair, or the anterior-lateral pair, or the posterior-lateral pair and the anterior-lateral pair; oppositisepalous; all alternating with the corolla members. Anthers connivent (in pairs, commonly), or separate from one another; dorsifixed; versatile, or non-versatile; dehiscing via longitudinal slits; introrse; unilocular (by abortion), or unilocular to bilocular, or unilocular and bilocular; tetrasporangiate; appendaged, or unappendaged. Pollen shed as single grains. Fertile gynoecium usually present, or absent (male flowers). Gynoecium 2 carpelled (the carpels deeply lobed to mimic G4). The pistil 4 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular (originally), or 4 locular (by intrusions of the ovary wall constituting ‘false septa’). Locules secondarily divided by ‘false septa’. Gynoecium median. Styles 1; when ‘apical’, from a depression at the top of the ovary (then the ovary deeply lobed); ‘gynobasic’ (usually), or apical. Stigmas 2, or 1 (by reduction); 2 - lobed; dry type; papillate; Group II type. Placentation basal. Ovules 2 per locule, or 1 per locule (two per original loculus, but one per locellus); ascending; apotropous; non-arillate; anatropous, or hemianatropous.

Fruit and seed features. Fruit usually non-fleshy, or fleshy (rarely); (more or less) a schizocarp (except perhaps in Eichlerago (= Prostanthera, where it has been described as non-schizocarpic, dry and indehiscent). Mericarps (2–)4; comprising nutlets (usually, typically of four nutlets, distinct or cohering pairwise, enclosed in the persistent calyx), or comprising drupelets (Prasieae). Seeds endospermic to non-endospermic (the scant, fleshy endosperm often absorbed by the developing embryo). Embryo well differentiated (with a downward-pointing radicle, by contrast with Boraginaceae). Cotyledons 2. Embryo achlorophyllous (16/23); straight. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C₃ and CAM.

Special features. Corolla tube straight, or curved, or bent. The upper lip of the corolla incorporating 2 members, the lower 3, or incorporating 4 members, the lower 1, or suppressed, the lower incorporating all five members.

Geography, cytology, number of species. World distribution: cosmopolitan. X = 5–11(+). 3500 species.

Economic uses, etc. The source, par excellence, of aromatic and antibiotic essential oils for the pharmaceutical and cosmetics industries (species of Salvia, Lavandula, Rosmarinus, Mentha, Marrubium, Pogostemon etc.), and of aromatic/flavoursome pot herbs (Salvia, Origanum, Thymus, Ocimum, Satureia etc.). Many are cultivated as ornamentals (Salvia, Ajuga, Physostegia, Monarda, Scutellaria, Nepeta, Teucrium, Stachys, Phlomis etc.).

Additional comments. Junell (1934), Erdtman (1945), Wunderlich (1967) and El-Gazzar and Watson (1970), all expressed dissatisfaction with traditional classifications of Lamiaceae (Lamiaceae), and with the circumscription of Lamiaceae relative to that of Verbenaceae sensu lato, based on very extensive comparative anatomical, palynological, phytochemical, morphological and host/parasite surveys. Their ideas, extended by morphological-cladistic and molecular studies, are now in process of being implemented formally in the shape of a fairly radically revised classification (cf. Cantino et al., 1992). The latter, however, is not yet available complete with the detailed, revised family descriptions necessary for incorporation in the present package.