Genus Corymbia K.D. Hill & L.A.S. Johnson, Telopea 6(2-3): ()

Type species: Corymbia gummifera (Gaertner) K.D. Hill & L.A.S. Johnson

Eucalyptus subseries Corymbosae Bentham, Fl. Austral. 3: 198, 253 (1867). Type: Eucalyptus gummifera (Gaertner) Hochr., lectotype designated by Blake (1953). Eucalyptus series Corymbosae Blakely, Key Eucalypts: 15 (1934); Blake, Austral. J. Bot. 1: 229 (1953).

Type: Eucalyptus dichromophloia F. Muell. was designated as lectotype by Chippendale (1988), who was misled by Blakely's invalid use of 'Corymbosae (Non-Peltatae)' and 'Corymbosae-Peltatae'. The names are best forgotten.

Generally trees; bark persistent, shortly fibrous-flaky, parting in small polygons, or smooth, excorticating in polygonal flakes or short strips (except in C. jacobsiana (section Fundoria)). Juvenile leaves opposite for few nodes (many nodes in series Ferrugineae), sometimes peltate, with single-celled simple trichomes arising from undifferentiated epidermis, and bristle-glands. Adult leaves disjunct, bristle-free (rarely opposite and with trichomes and bristle-glands). Lateral veins of adult leaves (except in neotenic forms) closely-spaced, branched, oblique, intramarginal vein close to the margin but usually distinct. Conflorescences anauxotelic or anthotelic, expanded terminal or lateral panicles or thyrsoids, sometimes metabotryoids, often extensively branched, with unit usually 7-flowered (occasionally 3-flowered) umbellasters. Oil ducts present in ovary and nectary (Carr & Carr 1969). Perianth 5-4-merous (flexible), carpels usually 3, sometimes varying in individual flowers to 4 or more rarely 2, or usually 4 in section Rufaria. Calyx calyptriform, persistent to anthesis, or caducous; corolla of ± free petals and ± adherent to calyx, or calyptriform. Petals (at least in primordia) differentiated into claw and limb. Stamens all fertile; anthers oblong to oblong-obovate, dorsifixed, versatile, dehiscing by parallel slits. Stigma shaggy or tapered, lobed or not lobed, with short or long papillae. Cotyledons reniform, relatively large, folded in embryo (not folded in section Blakearia). Ovules hemipterous, not regularly arranged in rows on the placenta. Ovulodes present. Inner integument partially resorbed. Seeds laterally or dorsiventrally compressed, in some groups with a terminal wing; hilum subterminal or ventral. Fruits medium-sized to large, urceolate to globular; capsule deeply sunken in the hypanthium, valves enclosed.

Diagnosis: Unicellular thin-walled hairs and frequently complex bristle-glands regularly present on juvenile shoots; bristle-gland cap cells 4, ornamented with micropapillae; xylem vessels solitary (Ingle & Dadswell 1953); inflorescences compound, terminal or lateral; calyx calyptriform; petals either free but closely appressed to the calycine calyptra and shed with it or ± united and calyptriform; cotyledons folded in embryo (not folded in section Blakearia); capsule sunken in fruit, disc depressed.

The name is from the Latin corymbium, a corymb, recalling the epithet Corymbosae used in subsectional or sectional rank under Eucalyptus by earlier authors and the name E. corymbosa, a long-standing synonym for the type species. In species with the plesiomorphic condition, inflorescences are corymbiform, though not corymbs in the precise sense.

Key to the sections

1 Seeds laterally compressed, often winged	Section Rufaria
1* Seeds dorsiventrally compressed, not winged
2 Calycine calyptra persistent to at or near anthesis
3 Bark mostly smooth
4 Fuits soft, fragile	Section Blakearia
4* Fuits hard, woody	Section Cadagaria
3 Bark mostly persistent	Section Ochraria
2* Calycine calyptra shedding long before anthesis
5 Bark wholly smooth	Section Ochraria
5* Bark mostly persistent
6 Bark stringy	Section Fundoria
6* Bark soft, scaly	Section Apteria