Family Sladeniaceae

Sladeniaceae Gilg & Werderm.) Airy Shaw

~ Theaceae

Habit and leaf form. Trees. Leaves alternate; non-sheathing; simple. Lamina entire; pinnately veined. Leaves exstipulate. Lamina margins serrate, or dentate.

Leaf anatomy. Stomata present; mainly confined to one surface (the lower); anomocytic.

The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses (no raphides).

Stem anatomy. Cork cambium present; initially superficial. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Vessel end-walls oblique; scalariform.

Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (from the lower, glandular ribs).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences axillary; short dichasial cymes. Flowers regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous; persistent; much imbricate. Corolla 5; 1 whorled; polypetalous (the petals as long as the sepals); imbricate; regular. Petals entire.

Androecium 10(–13). Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 10(–13); isomerous with the perianth to diplostemonous; filantherous (the filaments broad, more or less ovate, thick, abruptly attenuate above). Anthers basifixed (sagittate); dehiscing via pores (‘poriform slits’); introrse. Pollen grains aperturate; 3 aperturate; colporate (colporoidate).

Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior (ovary with 10 thickened and glandular ribs below, simulating a disk, and 20-ribbed above). Ovary 3 locular. Gynoecium stylate. Styles 1, or 3 (‘the ovary narrowed into a thick, shortly trifid style’); attenuate from the ovary; apical. Stigmas 3. Placentation axile, or apical. Ovules 2 per locule; pendulous; collateral; with a long, beaked appendage near the funicle.

Fruit non-fleshy; dehiscent, or a schizocarp (not known in the mature state — with crustaceous endocarp and papery exocarp, possibly splitting septicidally into three cocci). Mericarps if schizocarpic, 3. Seeds winged.

Geography, cytology. Paleotropical. Sub-tropical to tropical. Burma, Yunnan, Siam.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (?). Dahlgren’s Superorder Theiflorae (?); Theales (? - cf. Theaceae). Cronquist’s Subclass Dilleniidae; Theales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales.

Species 1. Genera 1; only genus, Sladenia.