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The families of flowering plants

L. Watson and M.J. Dallwitz

Ptaeroxylaceae Sonder

~ Sapindaceae, Rutaceae.

Habit and leaf form. Trees; bearing essential oils, or without essential oils (?); resinous, or not resinous (?). Leaves usually deciduous; alternate (Bottegoa, Cedrelopsis), or opposite (Ptaeroxylon); when alternate, spiral; petiolate; not gland-dotted; aromatic; compound; pinnate (pari- or (im)paripinnate, in Cedrelopsis and Ptaeroxylon, the leaflets opposite or alternate, oblique), or bipinnate (biparipinnate, Bottegoa). Lamina pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins (of the leaflets) entire.

Leaf anatomy. The leaf lamina dorsiventral (Ptaeroxylon), or bifacial (Cedrelopsis), or dorsiventral to bifacial (Bottegoa). Extra-floral nectaries present (on the leaves of Bottegoa and Ptaeroxylon), or absent (Cedrelopsis). Abaxial epidermis papillose, or not papillose. Mucilaginous epidermis absent. Stomata present; anomocytic (Bottegoa, Ptaeroxylon), or cyclocytic (Cedrelopsis). Adaxial hypodermis absent. Lamina without secretory cavities. The mesophyll with spherical etherial oil cells; without crystals.

Axial (stem, wood) anatomy. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The vessel end-walls horizontal to oblique; simple. The vessels without vestured pits. The axial xylem with libriform fibres; without septate fibres. The parenchyma scanty paratracheal, or apotracheal (scarce). ‘Included’ phloem absent.

Reproductive type, pollination. Unisexual flowers present. Plants polygamomonoecious, or dioecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, or in racemes. The ultimate inflorescence units cymose. Inflorescences axillary; small axillary cymes or false racemes. Flowers small; regular; 4 merous, or 5 merous; cyclic. Floral receptacle developing a gynophore (this slight, associated with the disk). Free hypanthium absent. Hypogynous disk present; intrastaminal.

Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx 4, or 5; 1 whorled; shortly gamosepalous; blunt-lobed, or toothed; regular; more or less imbricate. Corolla 4, or 5; 1 whorled; polypetalous; imbricate, or valvate.

Androecium 4, or 5. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4, or 5; isomerous with the perianth; oppositisepalous; filantherous (the filaments not basally flattened). Filaments not appendiculate (scaleless). Pollen shed as single grains. Pollen grains aperturate; 3–4 aperturate; colporate.

Gynoecium 2 carpelled (Bottegoa, Ptaeroxylon), or 3–5 carpelled (Cedrelopsis). Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 2–5 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 2–5 locular; subsessile, or stipitate (?). Gynoecium stylate. Styles 2–5; (shortly) partially joined. Stigmas 2–5; capitate. Ovules 1 per locule, or (1–)2(–3) per locule (Cedrelopsis); pendulous; apotropous; with dorsal raphe; non-arillate; campylotropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle.

Fruit non-fleshy; indehiscent (Bottegoa), or a schizocarp. Mericarps of schizocarps, 2–5; comprising follicles and samaroid (samaroid follicles, dehiscing via the inner suture). Fruit of Bottegoa, a samara (surrounded by a thin, broad wing). Seeds endospermic (the endosperm thin and fleshy), or non-endospermic; winged (above), or wingless (Bottegoa). Embryo curved, or bent. The radicle lateral.

Geography, cytology. Paleotropical and Cape. Tropical. Tropical and Southern Africa, Madagascar.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Rutales. Cronquist’s Subclass Rosidae; Sapindales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Sapindales (as a synonym of Rutaceae).

Species 4, or 5. Genera 3, or 4; Cedrelopsis, Ptaeroxylon, Bottegoa, (?)Kirkia.

General remarks. See Leroy 1959, Ptaeroxylaceae, in Compt. Rend. Acad. Sci. Paris 248, 1001–1003; Leroy 1960, Ptaeroxylaceae, in Journ. Agr. Trop. Bot. Appl. 7, 455–456; White and Styles 1966, Ptaeroxylaceae, in Flora Zambesiaca 2, 547–550; Van der Ham et al. 1995, Bottegoa in Kew Bull. 50, 243–265. Apart from the campylotropous, apotropus ovules with dorsal raphe, the data compiled for the present package have Ptaeroxylaceae differing from Rutaceae sensu stricto only in the mesophyll exhibiting etherial oil in cells rather than cavities.

Illustrations. • Cedrelopsis ambanjensis, C. gracilis and C. procera: Fl. Madagascar 1960s. • Cedrelopsis trivalvis: Fl. Madagascar 1960s.

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: 13th March 2017.’.