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The families of flowering plants

L. Watson and M. J. Dallwitz

Balanopaceae Benth.

Alternatively Balanopsidaceae.

Habit and leaf form. Trees, or shrubs; non-laticiferous. Leaves (pseudo-) whorled, or alternate; petiolate; non-sheathing; simple. Lamina pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or dentate.

Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (abaxial, the guard cells with well deveoped cuticular ridges); anomocytic. Adaxial hypodermis present. The mesophyll containing crystals (in at least some species). The crystals druses.

Axial (stem, wood) anatomy. The cortex containing cristarque cells, or without cristarque cells. Cork cambium present; initially superficial. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The vessel end-walls oblique; scalariform, or scalariform and simple. The axial xylem with fibre tracheids (B. balansae), or without fibre tracheids (B. microstachya); with libriform fibres (B. microstachya).

Reproductive type, pollination. Plants dioecious. Gynoecium of male flowers vestigial, or absent.

Inflorescence, floral, fruit and seed morphology. Flowers solitary (female), or aggregated in ‘inflorescences’ (male); when aggregated, in catkins (i.e. when male). Inflorescences of male flowers comprising catkins, the female flowers solitary. Flowers (both male and female) bracteate (the aggregated males with one subtending scale, the solitary females with many imbricating, involucral bracts).

Perianth vestigial (male calyx represented by a single unilateral scale), or absent (female).

Androecium in males (2–)5–6(–12). Stamens (2–)5–6(–12); filantherous to with sessile anthers (subsessile). Anthers basifixed; dehiscing via longitudinal slits; latrorse to introrse (latero-introrse). Pollen grains aperturate; 3–4(–5) aperturate; colpate; 2-celled.

Gynoecium 2–3 carpelled. The pistil 1 celled, or 2–3 celled. Gynoecium syncarpous; synovarious; superior. Ovary imperfectly 2–3 locular. Styles 2; free. Stigmas 2 (long, subulate). Placentation basal. Ovules 2 per locule; ascending; anatropous.

Fruit non-fleshy; indehiscent; a drupe. The drupes with separable pyrenes, or with one stone (with 1–2 1-seeded pyrenes). Seeds endospermic. Cotyledons 2. Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Alkaloids absent (one species).

Geography, cytology. Sub-tropical to tropical. Queensland, New Caledonia, Fiji. N = 21.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Balanopales. Cronquist’s Subclass Hamamelidae; Fagales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Malpighiales.

Species 12. Genera 1; only genus, Balanops.

Illustrations. • Technical details: Balanops (Hutchinson).

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: 19th October 2016.’.