Habit and leaf form. Trees, or shrubs; evergreen; bearing essential oils. Plants with neither basal nor terminal concentrations of leaves. Young stems cylindrical (hairy). To 3–8 m high. Leptocaul. Helophytic to mesophytic. Leaves small to medium-sized; opposite; decussate; ‘herbaceous’, or leathery; petiolate; gland-dotted; aromatic; edgewise to the stem, or with ‘normal’ orientation; simple; epulvinate. Leaf blades dorsiventral, or isobilateral, or centric; entire; flat; linear, or lanceolate, or oblong, or ovate; obovate, or elliptic; pinnately veined, or parallel-veined, or one-veined; cross-venulate, or without cross-venules. Mature leaf blades adaxially glabrous; abaxially glabrous. Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hairs absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous, or ornithophilous. Pollination mechanism unspecialized.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; axillary. Inflorescence few-flowered. Flowers in cymes. Inflorescences simple. The terminal inflorescence unit cymose. Inflorescences axillary. Flowers pedicellate (may be interpreted as pedunculate); (bi) bracteolate. Bracteoles persistent. Flowers small to large; regular, or somewhat irregular; zygomorphic. The floral asymmetry (when noticeable) involving the perianth. Flowers 4 merous; cyclic. Free hypanthium present (petals ‘inserted on the calyx’); obconic. Perianth with distinct calyx and corolla; 8; 2 -whorled; isomerous. Calyx present; 4; 1 -whorled; polysepalous; hairy (densely ciliate); imbricate, or valvate; regular, or unequal but not bilabiate (when lobes dimorphic, the inner lobes larger); green; persistent. Sepals elliptic to orbicular. Corolla present; 4; 1 -whorled; polypetalous; imbricate; regular; glabrous except for densely ciliate margin; plain; white. Petals orbicular. Corolla members entire. Androecial members indefinite in number. Androecium 50–150 (‘many’). Androecial members branched. Androecial sequence determinable, or not determinable. Androecial members maturing centripetally; free of the perianth; all equal, or markedly unequal; free of one another. Stamens 100 (‘many’); becoming exserted (equalling or exceeding the petals); all more or less similar in shape; polystemonous; alternisepalous and oppositisepalous; both opposite and alternating with the corolla members; erect in bud, or inflexed in bud. Anthers all alike; dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate; unappendaged (gland inconspicuous). Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary plurilocular; 2 locular. Epigynous disk present. Gynoecium stylate. Styles 1; apical. Stigmas 1. Placentation axile (centrally located). Ovules 6–14 per locule; pendulous to ascending; non-arillate; anatropous.
Fruit and seed features. Fruit fleshy; indehiscent; a berry; 2 celled; 1(–2) seeded. Seeds non-endospermic; winged, or wingless. Cotyledons 2; partly fused.
Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia and Queensland. Northern Botanical Province.
Etymology. After Francois Eugene, commonly called Prince Eugene of Savoy (1663–1736), one of the greatest generals of his time, in the service of Austria, who in the peace after 1718 cultivated the arts and developed a botanical garden near Vienna.