Family Tribelaceae

Tribelaceae (Engl.) Airy Shaw

~ Escalloniaceae, Grossulariaceae sensu lato

Habit and leaf form. Prostrate shrubs (the robust, flexuous stems bearing short, ascending leafy branches); not resinous. Leaves alternate; thickish, glaucescent above; sessile (semiamplexicaul); non-sheathing; simple. Lamina entire; ‘obscurely nerved’. Leaves exstipulate. Lamina margins apically minutely tri- dentate.

Leaf anatomy. Lamina without secretory cavities.

Stem anatomy. Secretory cavities absent. Secondary thickening developing from a conventional cambial ring (?).

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

Inflorescence, floral, fruit and seed morphology. Flowers solitary (at the apices of branchlets); regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5 (small); 1 whorled; shortly gamosepalous (below); regular; persistent; imbricate. Corolla 5 (relatively large); 1 whorled; polypetalous; contorted; regular; fleshy to not fleshy (‘thickish’). Petals slightly clawed; entire (elliptical).

Androecium 5. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments subulate). Anthers not becoming inverted during development; dehiscing via longitudinal slits; small, ovoid, extrorse.

Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles 1 (short, simple); apical. Stigmas 1; 3 lobed; capitate. Placentation axile. Ovules 30–50 per locule (‘many’); anatropous.

Fruit non-fleshy (the epicarp leathery, the endocarp crustaceous); dehiscent; a capsule. Capsules loculicidal and valvular (borne on a short, erect pedicel, the valves finally separating from the axis, to which the seeds long remain attached after the capsule has dehisced). Fruit many seeded. Seeds copiously endospermic. Endosperm oily. Testa smooth; black.

Geography, cytology. Neotropical and Antarctic. Pampas and Andean. Temperate. Temperate South America.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (?). Dahlgren’s Superorder Corniflorae (?); Cornales (?). Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level (?); Order Escalloniales (as a synonym of Escalloniaceae?).

Species 1. Genera 1; only genus, Tribeles.