The families of flowering plants
Habit and leaf form. Trees, or shrubs. Leaves evergreen, or deciduous; alternate; herbaceous, or leathery (sometimes holly-like); petiolate; non-sheathing; simple. Lamina entire. Leaves stipulate. Lamina margins serrate, or dentate (or spinose).
Leaf anatomy. Minor leaf veins without phloem transfer cells (Itea).
Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring.
Included phloem absent.
Reproductive type, pollination. Plants hermaphrodite, or polygamomonoecious.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in racemes, or in panicles. The ultimate inflorescence units cymose. Inflorescences terminal, or axillary; densely elongate-racemiform or shortly cymose. Flowers small; fragrant; regular; 5 merous; cyclic; tetracyclic. Free hypanthium present (as a turbinate calyx tube). Hypogynous disk (or perigynous disk) present; intrastaminal; annular.
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous (on the hypanthium); regular; persistent; valvate, or open in bud. Corolla 5; 1 whorled; polypetalous (the petals narrow); valvate; regular; white.
Androecium 5. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous (?); filantherous (the filaments subulate). Anthers dorsifixed; non-versatile; dehiscing via longitudinal slits; introrse (oblong or ovate). Pollen grains aperturate; 2(–3) aperturate; porate.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; synovarious, or eu-syncarpous (the two connate styles finally becoming free, or remainong united by the capitate stigma); superior to partly inferior. Ovary 2 locular. Gynoecium stylate. Styles 2; free, or partially joined (initially connate, subsequently free or remaining joined only by the stigma); apical. Placentation axile. Ovules 4–50 per locule (few to many); usually biseriate.
Fruit non-fleshy; dehiscent; a capsule (narrow or ovoid). Capsules septicidal. Seeds sparsely endospermic. Endosperm fleshy. Seeds flattened, oblong or scobiform. Embryo well differentiated (large).
Physiology, phytochemistry. Cyanogenic. Cynogenic constituents tyrosine-derived (triglochinin?). Proanthocyanidins present; delphinidin. Flavonols absent. Ellagic acid absent (Itea).
Geography, cytology. Holarctic, Paleotropical, and Cape. Temperate to tropical. East and Southeast Asia, eastern North America, tropical and South Africa.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Rosiflorae; Cunoniales. Cronquists Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales.
Species 17. Genera 2; Itea, Choristylis.
General remarks. Bohm et al. (1988) provided details of Itea flavonoids.
Illustrations. • Itea ilicifolia: Hook. Ic. Pl. 16 (1886). • Itea ilicifolia and I. macrophylla, with Quintinia serrata and Cyrilla racemiflora (as Itea virginica): Nat. Pflanzenfam. III. • Itea spinosa and Cyrilla racemiflora (as I. virginica): Bot Mag. 42 (1815, N 1767) and 50 (1823, N 2409).
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: 24th October 2017. delta-intkey.com/angio’.