Habit and leaf form. Trees, or shrubs; non-laticiferous and without coloured juice. Leaves (pseudo-) whorled, or alternate; petiolate; non-sheathing; simple. Lamina pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or dentate.
Leaf anatomy. Stomata present; anomocytic.
Adaxial hypodermis present. Lamina dorsiventral.
Stem anatomy. Cork cambium present; initially superficial. The cortex containing cristarque cells, or without cristarque cells. Secondary thickening developing from a conventional cambial ring. Xylem with fibre tracheids; with vessels. Vessel end-walls oblique; scalariform, or scalariform and simple.
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, biochemistry. 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 (1998) Eudicot; core Eudicot; Rosid; Eurosid I. APG 3 (2009) Order: Malpighiales.
Species 12. Genera 1; only genus, Balanops.