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The families of flowering plants

L. Watson and M. J. Dallwitz

Theaceae D. Don

Including Camelliaceae Dum., Malachodendreae (Malachodendraceae) J.G. Agardh, Ternstroemiaceae Mirb.; excluding Asteropeiaceae, Bonnetiaceae, Sladeniaceae.

Habit and leaf form. Trees and shrubs. Mesophytic. Leaves evergreen; alternate; spiral; leathery; petiolate; non-sheathing; not gland-dotted; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or serrate. Leaf development not ‘graminaceous’. Domatia occurring in the family (recorded in Eurya); manifested as pits.

Leaf anatomy. The leaf lamina usually dorsiventral (with two or three layers of palisade). Mucilaginous epidermis present, or absent. Stomata mainly confined to one surface (abaxial); anomocytic, or cyclocytic. Hairs infrequently present, or absent; when present, eglandular (ocasionally fasciculate); usually unicellular. Unicellular hairs acuminate, simple (and thick-walled). Adaxial hypodermis present, or absent. Lamina without secretory cavities. The mesophyll commonly with sclerenchymatous idioblasts (varying in shape from genus to genus); commonly containing crystals. The crystals druses, or solitary-prismatic. Minor leaf veins without phloem transfer cells (4 genera).

Axial (stem, wood) anatomy. Young stems with solid internodes. Pith with diaphragms, or without diaphragms; homogeneous, or heterogeneous. Secretory cavities absent. Cork cambium present; initially deep-seated, or initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The wood semi-ring porous to diffuse porous. The vessels very small to medium; predominantly or exclusively solitary. The vessel end-walls horizontal to oblique, or oblique; scalariform (with numerous bars). The vessels with spiral thickening, or without spiral thickening. The axial xylem with tracheids, or without tracheids; with vasicentric tracheids, or without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (usually), or apotracheal and paratracheal (in a few genera). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified. ‘Included’ phloem absent. The wood not storied. Tyloses present (sometimes), or absent.

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

Inflorescence, floral, fruit and seed morphology. Flowers usually solitary (and axillary); bi- bracteolate; medium-sized, or large; regular; cyclic, or partially acyclic. When partially acyclic, the perianth acyclic (or somewhat so).

Perianth with distinct calyx and corolla, or sequentially intergrading from sepals to petals; 9–12(–50) (i.e. rarely ‘many’); (when cyclic) isomerous, or anisomerous. Calyx 5, or 7; 1 whorled; gamosepalous (usually); regular; persistent; non-accrescent; imbricate. Corolla (4–)5(–50) (rarely ‘many’); polypetalous, or gamopetalous (sometimes basally connate). Corolla lobes markedly longer than the tube. Corolla imbricate; regular.

Androecium 5, or 10, or 15, or 16–100 (usually ‘many’). Androecial members branched, or unbranched; when many (i.e. usually), maturing centrifugally; free of the perianth, or adnate (to the perianth); free of one another, or coherent; when coherent 1 adelphous (the filaments united in a tube), or 5 adelphous (when bundled); 1–5 whorled. The androecial bundles at least sometimes opposite the corolla members. Androecium exclusively of fertile stamens. Stamens 5, or 10, or 15, or 16–100 (usually ‘many’); isomerous with the perianth to triplostemonous (rarely), or polystemonous (usually); alternisepalous (at least, the bundles sometimes so). Anthers dorsifixed, or basifixed; versatile, or non-versatile; dehiscing via longitudinal slits (usually), or dehiscing via short slits; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer, or initially with more than one middle layer (1 to 3). Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate (colporoidate); 2-celled.

Gynoecium (2–)3–5(–10) carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth, or increased in number relative to the perianth. The pistil (2–)3–5(–10) celled. Gynoecium syncarpous; synovarious to synstylovarious, or semicarpous (carpels united only basally in some Camellia spp.); superior (usually), or partly inferior (Visnea etc.), or inferior (Symplocarpon). Ovary (2–)3–5(–10) locular. Gynoecium stylate. Styles 2–5(–10) (as many as G); free, or partially joined. Stigmas wet type; papillate; Group III type. Placentation axile. Ovules (2–)4–50 per locule (i.e. to ‘many’); pendulous; anatropous, or campylotropous (weakly); bitegmic; tenuinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3 (remaining uninucleate); not proliferating. Synergids pear-shaped. Hypostase present. Endosperm formation nuclear. Embryogeny solanad.

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry, or a drupe. Capsules usually loculicidal (with a persistent columella). Seeds non-endospermic (usually), or endospermic (e.g. Visnea). Endosperm in Visnea oily. Seeds conspicuously hairy, or not conspicuously hairy. Cotyledons 2 (large). Embryo achlorophyllous (2/2); straight, or curved.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. Not cyanogenic. Alkaloids present, or absent. Iridoids not detected. Proanthocyanidins present (usually), or absent; cyanidin, or delphinidin, or cyanidin and delphinidin. Flavonols present, or absent; kaempferol and quercetin, or kaempferol, quercetin, and myricetin. Ellagic acid present (6 species, 5 genera), or absent (2 out of 4 Camellia species). Aluminium accumulation demonstrated (often), or not found.

Geography, cytology. Sub-tropical and tropical. Pantropical and subtropical. X = 15, 18, 21, 25.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Theiflorae; Theales. Cronquist’s Subclass Dilleniidae; Theales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales.

Species 500. Genera 18; Adinandra, Anneslea, Apterosperma, Archboldiodendron, Balthasaria, Camellia (including Thea), Cleyera, Eurya, Ficalhoa(?), Franklinia, Freziera, Gordonia, Pyrenaria, Schima, Stewartia, Symplocarpon, Ternstroemia (referred to Pentaphylacaceae by APG), Visnea.

Economic uses, etc. Includes the commercial tea plant (Camellia sinensis), and many cultivated ornamentals.

Illustrations. • Technical details: Camellia, Thea, Gordonia. • Technical details: Gordonia, Ternstroemia. • Technical details: Visnea (Thonner). • Camellia japonica: Bot. Mag. 2, 1788. • Malachodendron ovatum, probably = Stewartia malachodendron: Bot. Reg. 1104, 1827. • leaf anatomical details of Cleyera and Freziera, with Saurauia (Actinidiaceae) and Caraipa (Guttiferae): Solereder, 1908.

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: 19th October 2016.’.