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The families of flowering plants

L. Watson and M.J. Dallwitz

Bretschneideraceae Engl. & Gilg

~ Akaniaceae.

Habit and leaf form. Trees (with myrosin cells in bark and inflorescence). Leaves deciduous; alternate; petiolate; compound; (impari-) pinnate. Lamina pinnately veined. Leaves exstipulate.

Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays mainly wide. The axial xylem with vessels.

The wood semi-ring porous (the growth rings inconspicuous). The vessel end-walls scalariform and simple (mostly with simple perforations, but some scalariform with aberrant, cross-linking bars — cf. Akania). The axial xylem without fibre tracheids; with libriform fibres. The parenchyma scanty paratracheal. ‘Included’ phloem absent.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence units racemose. Inflorescences terminal. Flowers rather large, or medium-sized; somewhat irregular; slightly zygomorphic. The floral irregularity involving the perianth. Free hypanthium present (the flower perigynous, the corolla inserted on the ‘calyx tube’). Hypogynous disk present; extrastaminal (?); annular.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous; five toothed; campanulate. Corolla 5; 1 whorled; polypetalous; imbricate; unequal but not bilabiate; pink. Petals clawed.

Androecium 8. Androecial members free of the perianth (attached to the nectary disk). Androecium exclusively of fertile stamens. Stamens 8 (declinate); almost diplostemonous; both alternating with and opposite the corolla members; filantherous (the filaments hairy). Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate; bi-apiculate. Endothecium developing fibrous thickenings. Anther epidermis persistent (tanniferous). The initial microspore tetrads tetrahedral (usually), or isobilateral. Anther wall initially with more than one middle layer (2 layers). Tapetum glandular. Pollen grains aperturate; (2–)3 aperturate; colpate; 2-celled.

Gynoecium 3(–5) carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 3(–5) celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 3(–5) locular. Gynoecium stylate. Styles 1; apical (long, curved). Stigmas 1; capitate. Placentation axile to apical. Ovules 2–3 per locule; pendulous; non-arillate; campylotropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Allium-type. Antipodal cells formed; not proliferating; ephemeral. Hypostase present. Endosperm formation nuclear.

Fruit non-fleshy; dehiscent; a capsule (thick-walled). Capsules obovate, 3(–5) valved. Seeds non-endospermic. Embryo well differentiated (large). Cotyledons 2. Embryo straight. Testa red.

Physiology, phytochemistry. Mustard-oils present.

Geography, cytology. Holarctic. China. X = 9.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Violiflorae; Capparales (re-assigned from Sapindales). Cronquist’s Subclass Rosidae; Sapindales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Brassicales (as a synonym of Akaniaceae).

Species 1 (Bretschneidera sinensis). Genera 1; only genus, Bretschneidera.

General remarks. Carlquist (1996) considered the wood very like that of Akania. However, comparing these compiled descriptions shows Bretschneidera differing from Akania (q.v.) in 14 characters representing leaf, inflorescence and floral (perianth, androecium) morphology, ovule and seed details, and embryology.

Illustrations. • Bretschneidera sinensis: Hook. Ic. Pl. 28 (1901).

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: 5th March 2018.’.