Family Tetracarpaeaceae

Tetracarpaeaceae (Engl.) Nak.

~ Escalloniaceae, Grossulariaceae, Saxifragaceae

Habit and leaf form. Low shrubs. Plants non-succulent. Leptocaul. Mesophytic. Leaves evergreen; small; alternate; leathery; petiolate; non-sheathing; not gland-dotted; simple. Lamina entire; oblong, or ovate; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins doubly serrate. Leaves without a persistent basal meristem.

Stem anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence unit racemose. Inflorescences terminal; erect racemes. Flowers bracteate; small; regular; 4–5 merous; cyclic; pentacyclic. Free hypanthium present (?— with a short ‘calyx tube’).

Perianth with distinct calyx and corolla; 8, or 9; 2 whorled; isomerous, or anisomerous. Calyx 4, or 5; 1 whorled; shortly gamosepalous (basally). Calyx lobes markedly longer than the tube. Calyx regular; persistent; imbricate. Corolla 4; 1 whorled; polypetalous; imbricate; regular; white; deciduous (caducous). Petals clawed.

Androecium 8. Androecial members free of the perianth; coherent; 1 adelphous (the filaments very shortly connate); 2 whorled. Androecium exclusively of fertile stamens. Stamens 8; diplostemonous; both alternating with and opposite the corolla members. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; latrorse. Pollen grains aperturate; 3 aperturate; colpate (?).

Gynoecium 4 carpelled. Carpels isomerous with the perianth. Gynoecium apocarpous; eu-apocarpous; superior. Carpel sub non-stylate; apically stigmatic; 15–100 ovuled (‘many’). Placentation marginal (ventral). Ovules anatropous; unitegmic; embryology not recorded.

Fruit fleshy; an aggregate. The fruiting carpel dehiscent; a follicle. Fruit 15–100 seeded (‘many’). Seeds endospermic.

Geography, cytology. Temperate. Tasmania.

Taxonomy. Subclass Dicotyledonae; Crassinucelli, or Tenuinucelli (? — polypetalous, but exstipulate and with unitegmic ovules). Dahlgren’s Superorder Corniflorae (?); Cornales (?). Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales.

Species 1. Genera 1; only genus, Tetracarpaea.