Family Donatiaceae

Donatiaceae (Mildbr.) Skottsb.

~ Stylidiaceae

Habit and leaf form. Cushion-forming, mosslike herbs. Perennial; with neither basal nor terminal aggregations of leaves. Mesophytic, or xerophytic. Leaves alternate; spiral; imbricate; non-sheathing; simple; epulvinate. Lamina entire; linear. Leaves exstipulate; without a persistent basal meristem.

Leaf anatomy. Stomata present; anomocytic, or paracytic.

The mesophyll containing mucilage cells.

Stem anatomy. Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening absent (?), or developing from a conventional cambial ring. Vessel end-walls oblique; scalariform.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; terminal (sessile); regular to somewhat irregular. The floral irregularity involving the perianth (the calyx). Flowers cyclic; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 1–20; 2 whorled; isomerous, or anisomerous. Calyx 5–7; 1 whorled; gamosepalous; funnel-shaped to tubular; imbricate, or open in bud (?). Corolla 5–10; 1 whorled; polypetalous; imbricate; more or less fleshy.

Androecium 2, or 3. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 2, or 3; reduced in number relative to the adjacent perianth. Anthers extrorse. Pollen grains aperturate; 3(–4) aperturate; colporate.

Gynoecium 2 carpelled, or 3 carpelled. The pistil 2 celled, or 3 celled. Gynoecium syncarpous; synovarious; inferior. Ovary 2 locular, or 3 locular. Epigynous disk present. Styles 2, or 3 (one per carpel); free; apical. Placentation axile. Ovules 15–100 per locule (‘many’); non-arillate.

Fruit non-fleshy; indehiscent; capsular-indehiscent. Seeds copiously endospermic. Endosperm oily. Embryo well differentiated (but minute). Cotyledons 2.

Physiology, biochemistry. Iridoids not detected (S.R. Jensen, unpublished). Inulin recorded.

Geography, cytology. Frigid zone and temperate. Tasmania, New Zealand, subantarctic South America.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Asteridae; Campanulales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Asterales (as a synonym of Stylidiaceae?).

Species 2. Genera 1; only genus, Donatia.