Habit and leaf form. Trees (with peltate-scaly indumentum); bearing essential oils; leptocaul. Mesophytic. Leaves alternate; spiral; petiolate; non-sheathing; gland-dotted; aromatic; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire. Leaves without a persistent basal meristem.
Leaf anatomy. Hairs present. Complex hairs present; peltate (fimbriate).
Lamina dorsiventral. The mesophyll with spherical etherial oil cells.
Stem anatomy. Cork cambium present; initially superficial. Nodes bilacunar (but with three traces, according to Lammers et al. 1986), or tri-lacunar (?). Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. ‘Included’ phloem absent. Xylem with fibre tracheids. Vessel end-walls simple, or scalariform and simple. Wood parenchyma apotracheal (continuous-banded). Sieve-tube plastids S-type. Pith with diaphragms.
Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary (or paired, on axillary short-shoots). Bracts calyptrate, or not calyptrate. Flowers large; calyptrate (calyptra representing either bracts or an outer perianth whorl); regular; partially acyclic. The perianth acyclic, the androecium acyclic, and the gynoecium acyclic. Free hypanthium absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; 9–11. Calyx 4, or 6; 1 whorled; gamosepalous; calyptrate (i.e the inner whorl of the bracts/perianth conundrum also calyptrate). Corolla 7–9 (merging acropetally into the androecium); polypetalous; imbricate; regular; white, or red. Petals narrow.
Androecium 25–40. Androecial members maturing centripetally; free of the perianth; free of one another; spiralled. Androecium including staminodes. Staminodes 8–10; internal to the fertile stamens; non-petaloid (subulate). Stamens about 15–35; laminar to petaloid. Anthers adnate; non-versatile; dehiscing by longitudinal valves; extrorse (the thecae abaxial). Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate.
Gynoecium (6–)7–10(–28) carpelled; apocarpous; eu-apocarpous to semicarpous (at first free, but soon concrescent); superior. Carpel apically stigmatic; 1(–2) ovuled. Placentation apical, or marginal. Ovules non-arillate; anatropous.
Fruit fleshy; if the original carpels seen as individual fruits, an aggregate. The fruiting carpels coalescing into a secondary syncarp (i.e. the carpels of the one gynoecium fusing to form a fleshy, gall-like syncarp). Seeds endospermic. Endosperm not ruminate; oily.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Alkaloids present (4 species). Iridoids not detected.
Geography, cytology. Tropical. Eastern Malaysia and Northern Australia. 2n = 24.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Magnoliales. Cronquist’s Subclass Magnoliidae; Magnoliales. APG 3 core angiosperms; Superorder Magnolianae; Order Magnoliales.
Species 2. Genera 1; only genus, Galbulimima.