| | The Families of Angiosperms |
~ Theaceae.
Habit and leaf form. Trees. Leaves persistent; alternate; flat; ‘herbaceous’ to leathery; petiolate; non-sheathing; simple. Lamina entire; pinnately veined; attenuate to the base. Leaves exstipulate. Lamina margins serrate, or dentate.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (the lower); anomocytic. The mesophyll containing crystals. The crystals druses (no raphides).
Axial (stem, wood) anatomy. Young stems with solid internodes. Pith homogeneous. Cork cambium present; initially superficial. Internal phloem absent. Secondary thickening developing from a conventional cambial ring.
The vessel end-walls oblique; scalariform. ‘Included’ phloem absent.
Reproductive type, pollination. Unisexual flowers absent. 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 units cymose. Inflorescences axillary; short dichasial cymes. Flowers regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; usually 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 (8–)10(–13). Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (8–)10(–13); isomerous with the perianth to diplostemonous; filantherous (the filaments broad, more or less ovate, thick, abruptly attenuate above). Anthers hairy, sagittate, basifixed; 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 III core angiosperms; core eudicot; Superorder Asteranae. APG IV Order Ericales.
Species 1. Genera 1 (with Ficalhoa not included); only genus, Sladenia (S. celastrifolia).
Illustrations. • Sladenia celastrifolia: Hook. Ic. Pl. 31 (1915).
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: 25th September 2025. delta-intkey.com’.
