The families of flowering plants

L. Watson and M.J. Dallwitz

Tetrachondraceae Skottsb.

~ Labiatae.

Excluding Polypremaceae.

Habit and leaf form. Small, branched, creeping herbs; bearing essential oils. Plants succulent. Perennial (with prostrate, rooting stems emitting short, erect, leafy branches). Leaves opposite; leathery (the blades); petiolate (the petioles flattened); connate (by the petioles); obscurely gland-dotted; aromatic; simple. Lamina entire. Leaves exstipulate. Lamina margins minutely denticulate.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; terminal, or axillary; regular; 4 merous; cyclic; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 8; 2 whorled; isomerous. Calyx 4; 1 whorled; gamosepalous; regular; imbricate (?); with the median member anterior. Corolla 4; 1 whorled; gamopetalous; sub- rotate; regular.

Androecium 4. Androecial members adnate (epipetalous); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers dorsifixed; introrse. Pollen grains aperturate; 3 aperturate; colporate (colporoidate).

Gynoecium 2 carpelled (but ostensibly four, the carpels being deeply lobed, cf. Labiatae). Carpels isomerous with the perianth (ostensibly), or reduced in number relative to the perianth (?). The pistil 4 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 4 locular (ostensibly), or 2 locular (with four locellae via false septa, cf. Labiatae?). Locules secondarily divided by ‘false septa’, or without ‘false septa’ (?). Gynoecium stylate. Styles 1 (slender, long or short); ‘gynobasic’. Stigmas 1 (inconspicuous). Placentation basal. Ovules 1 per locule (ostensibly), or 2 per locule (if the apparent locules are interpreted as locelli); ascending; anatropous.

Fruit non-fleshy; a schizocarp. Mericarps comprising nutlets. Fruit of four one-seeded, setulose nutlets. Seeds copiously endospermic.

Geography, cytology. Antarctic. Temperate. New Zealand, Patagonia.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Lamiiflorae; Lamiales (?). Cronquist’s Subclass Asteridae; Lamiales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Lamiales.

Species 2. Genera 1; only genus, Tetrachondra.

Illustrations. • Tetrachondra hamiltonii: Hook. Ic. Pl. 23 (1894).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.