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The families of flowering plants

L. Watson and M.J. Dallwitz

Aegicerataceae Blume

~ Myrsinaceae.

Habit and leaf form. Small trees, or shrubs (mangroves, with the habit of Rhizophora). Helophytic. Leaves alternate; leathery; non-sheathing; gland-dotted (punctate); simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire.

Leaf anatomy. The leaf lamina dorsiventral. Hairs present (comprising or including sunken, peltate trichomes). Lamina with secretory cavities. Secretory cavities schizogenous (with yellow or reddish brown contents).

Axial (stem, wood) anatomy. Secretory cavities present (schizogenous, with yellow or reddish-brown contents, in pith ad cortex). Cork cambium present; initially superficial. Primary vascular tissues in a cylinder, without separate bundles, or comprising a ring of bundles (?); collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays wide, or wide and mixed wide and narrow.

The wood diffuse porous. The vessels small; in radial multiples and clustered, or in tangential arcs. The vessel end-walls simple. The vessels without vestured pits; without spiral thickening. The axial xylem without fibre tracheids; with libriform fibres; without septate fibres. The fibres without spiral thickening. The parenchyma paratracheal; wood storied.

Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite; viviparous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in umbels. Inflorescences terminal, or axillary; sessile terminal or axillary umbels, or short branched racemes. Flowers ebracteate; ebracteolate; small; somewhat irregular to very irregular; asymmetric. The floral irregularity involving the perianth (the calyx). Flowers 5 merous; cyclic; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous (leathery); unequal but not bilabiate; dextrorsely contorted. Corolla 5; 1 whorled; gamopetalous (shortly tubular). Corolla lobes about the same length as the tube, or markedly longer than the tube. Corolla dextrorsely contorted; more or less regular (the lobes soon reflexing); leathery.

Androecium 5. Androecial members adnate (inserted in the hairy corolla tube); coherent (the filaments shortly connate); 1 adelphous; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; alternisepalous; opposite the corolla members. Anthers dehiscing via longitudinal slits; introrse; bilocular (the loculi internally transversely septate); tetrasporangiate.

Gynoecium 3–5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1. Placentation free central. Ovules in the single cavity 30–100 (‘many’); horizontal to ascending; anatropous; unitegmic; crassinucellate. Endosperm formation nuclear (but with subsequent centripetal wall formation). Endosperm haustoria present; from secondary endosperm tissue, invading funicle and integument.

Fruit non-fleshy; ultimately dehiscent; a capsule to capsular-indehiscent (cylindrical, arcuate, longitudinally ribbed); 1 seeded. Seeds non-endospermic. Embryo well differentiated (germinating within the pericarp). Cotyledons connate into a tube enclosing the plumule. Embryo bent (cylindrical).

Physiology, phytochemistry. Anatomy non-C4 type. Not cyanogenic. Iridoids not detected. Saponins/sapogenins present. Proanthocyanidins present.

Special distinguishing feature. Mangroves.

Geography, cytology. Paleotropical and Australian. Tropical. Palaeotropical.

Taxonomy. Subclass Dicotyledonae; Crassinucelli, or Tenuinucelli (? - ovules crassinucellate but unitegmic). Dahlgren’s Superorder Primuliflorae; Primulales. Cronquist’s Subclass Dilleniidae; Primulales. APG III core angiosperms; core eudicot; Superorder Asteranae. APG IV Order Ericales (as a synonym of Myrsinaceae).

Species 2. Genera 1; Aegiceras.

General remarks. Differing from Myrsinaceae sensu stricto (q.v.) in mangrove habit, the more or less irregular calyx, capsular fruits, and non-endospermic seeds with bent embryo and lacking amyloid; also in the crassinucellate (but unitegmic) ovules.

Illustrations. • Aegiceras majus: R. Wight 2 (1850). • Le Maout and Decaisne: Aegiceras. • Leaf hairs of Aegiceras majus, with Myrsinaceae (Ardisia) and Theophrastaceae (Clavija and Jacquinia): 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: 15th April 2018.’.