Brexiaceae Lindl.
~ Escalloniaceae, Grossulariaceae
Including Ixerbaceae, Rousseaceae DC.
Habit and leaf form. Small trees, or shrubs; resinous (at least sometimes), or not resinous. Leaves well developed. Leaves evergreen; alternate, or opposite, or whorled; leathery; petiolate; simple. Lamina entire; pinnately veined; cross-venulate. Leaves stipulate (Brexia), or exstipulate. Stipules when present, intrapetiolar; minute, caducous. Lamina margins entire, or serrate, or dentate.
Leaf anatomy. Lamina dorsiventral. Minor leaf veins without phloem transfer cells (Brexia).
Stem anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Vessel end-walls scalariform and simple, or simple. Wood parenchyma apotracheal.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes. The terminal inflorescence unit cymose. Inflorescences terminal and axillary (few flowered); few-flowered axillary cymes. Flowers medium-sized to large; regular; 4–6 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; intrastaminal (conspicuous); of separate members (e.g. as palmate scales opposite the petals), or annular.
Perianth with distinct calyx and corolla; 8–12; 2 whorled; isomerous. Calyx 4–6; 1 whorled; polysepalous; regular; persistent, or not persistent; imbricate, or valvate. Corolla 4–6; 1 whorled; polypetalous, or gamopetalous; imbricate, or contorted (when polypetalous), or valvate (when sympetalous); persistent, or deciduous. Petals when free, clawed.
Androecium 4–6, or 8–12 (if interstaminal scales are regarded as staminodal). Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens, or including staminodes (allowing for the interstaminal scales). Staminodes (if so interpreted) 4–6; more or less petaloid. Stamens 4–6; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (with large anthers). Anthers dorsifixed; non-versatile; dehiscing via longitudinal slits; introrse. Pollen with viscin strands (the grains cohering). Pollen grains aperturate; 3–5 aperturate; colporate.
Gynoecium 4–7 carpelled. Carpels isomerous with the perianth to increased in number relative to the perianth. The pistil 4–7 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 4–6(–7) locular. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; truncate, or capitate; dry type; non-papillate; Group II type. Placentation axile. Ovules 2–50 per locule (to ‘many’); funicled; horizontal; apotropous; collateral, or biseriate; anatropous; bitegmic. Endothelium differentiated. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids elongated. Endosperm formation nuclear.
Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry, or a drupe. Capsules when capsular, loculicidal (Ixerba). The drupes with one stone (one-celled). Seeds almost non-endospermic (? see Lindley 1853). Embryo straight.
Physiology, biochemistry. Not cyanogenic.
Geography, cytology. Paleotropical and Antarctic. Sub-tropical to tropical. East Africa, Madagascar, Mascarene Is., New Zealand.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Saxifragales. Cronquist’s Subclass Rosidae; Rosales. APG (1998) Eudicot; core Eudicot; Rosid; unassigned to Eurosid I or Eurosid II, or Eurosid I; (if ‘unclassified Rosid’) unassigned to order; (if Eurosid I) unassigned at ordinal level (as a synonym of Celastraceae). Species 11. Genera 3; Brexia, Ixerba, Roussea.
APG (1998) list ‘Ixerbaceae’ as unclassified Rosid, then list Brexiaceae as a synonym ofCelastraceae.
Illustrations. • Technical details. • Technical details.
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
