Eucalyptus melanoleuca

Eucalyptus | Symphyomyrtus | Adnataria | Terminales | Rhodoxylon | Concolores

Eucalyptus melanoleuca S.T.Blake, Austrobaileya 1: 6 (1977).

T: Queensland: 6–7 miles [c. 10–11 km] N of Yarraman, July 1952, S.T.Blake 18975; holo: BRI; iso: CANB, NSW, K.

Tree to 30 m tall. Forming a lignotuber.
Ironbark, dark grey to black. Branches c. 5 cm diameter or narrower with white smooth bark.
Oil glands sometimes present in the pith of the branchlets.
Juvenile growth (coppice or field seedlings to 50 cm): stem square to round in cross-section; juvenile leaves opposite for a few pairs, becoming alternate, shortly petiolate, ovate, 4.5–8.5(10) cm long, 2–4 cm wide, green.
Adult leaves alternate, petiole (1)1.2–2(2.5) cm long; blade lanceolate, rarely falcate, (7)8.5–14.5(15) cm long, 1.5–3.5 cm wide, base tapering to petiole, concolorous to slightly discolorous, glossy, green, side-veins usually at an angle less than 45° to the midrib, very densely reticulate, intramarginal vein parallel to and well removed from the margin, oil glands intersectional.
Inflorescence terminal compound, or axillary compound or sometimes axillary single, peduncles 0.5–1.5 cm long, buds 7 per umbel, pedicels 0.2–0.7 cm long. Mature buds obovoid to ovoid to slightly pyriform, 0.5–0.9 cm long, 0.3–0.6 cm wide, scar present (outer operculum shed early), inner operculum conical to rarely slightly beaked and slightly narrower and much shorter than the hypanthium, hypanthium sometimes weakly ribbed, stamens inflexed, the outer filaments lacking anthers (staminodes), anthers adnate, basally attached and positioned obliquely at filament tip, cuboid, dehiscing by terminal pores, style long, stigma pin-head, locules 4 or 5, the placentae each with 4 vertical ovule rows. Flowers white.
Fruit on pedicels 0.1–0.5 cm long, barrel-shaped to cup-shaped or ± obconical, 0.4–0.7(0.9) cm long, 0.4–0.6 cm wide, occasionally ribbed on the lower part of the hypanthium, disc descending, valves 4 or 5, enclosed.
Seeds brown, 1–2 mm long, flattened-ovoid, shallowly reticulate, hilum ventral.

Cultivated seedlings (measured at ca node 10): cotyledons reniform to oblong; stems square in cross-section, sometimes weakly winged; leaves sessile to shortly petiolate, opposite for ca 3 to 5 nodes then alternate, ovate tending to lanceolate, 4.5–9.5 cm long, 1.6–4.5 cm wide, base tapering, discolorous, glossy dark green above, paler under.

Flowering has been recorded in February, June, July, August and September.

A medium to tall ironbark tree endemic to south-east Queensland from Inglewood to just south-east of Toowoomba, north through the Nanango–Yarraman–Gayndah–Monto region to the Blackdown Tablelands area. Characterised by the contrasting black rough bark on the trunk and the white smooth bark on the branches, concolorous glossy adult leaves, terminal inflorescences, buds with staminodes, small barrel-shaped fruit with four or five valves and ovate juvenile leaves.

Within its subgroup, i.e. subseries Concolores, E. melanoleuca is closest to E. dura, E. ancophila, E. fusiformis, E. corynodes and E. tetrapleura. All have ovate to broadly lanceolate to lanceolate juvenile leaves. E. dura differs only marginally by having slightly longer lanceolate to broadly lanceolate juvenile leaves (E. melanoleuca with shorter ovate juveniles). E. ancophila differs by having larger, slightly discolorous adult leaves. E. fusiformis differs by having dull adult leaves. E. corynodes differs by having glaucous to blue-grey adult leaves. E. tetrapleura has dull adult leaves and larger distinctly four-sided buds and fruit.

Eucalyptus suffulgens, E. panda, E. beyeri, E. virens and E. sicilifolia, also members of the subseries Concolores, differ by having much narrower lanceolate to linear juvenile leaves (ovate in E. melanoleuca). The two subspecies in E. caleyi both have dull glaucous adult leaves. E. caleyi subsp. ovendenii differs further by having distinctly four-sided buds and fruit.

All the species in the subseries Discolores, i.e. E. paniculata, E. decolor, E. placita and E. sp. Dorsiventralis, differ by having distinctly discolorous adult leaves (E. melanoleuca with concolorous to slightly discolorous adult leaves). E. sp. Dorsiventralis differs further by having four-sided fruit.

Within its area of occurrence there are other ironbarks which may be confused with E. melanoleuca. They are E. beaniana, E. crebra, E. decorticans, E. fibrosa subsp. fibrosa, E. fibrosa subsp. nubila, E. melanophloia, E. rhombica, E. siderophloia and E. taurina, all of which differ in having buds with stamens all fertile and irregularly flexed.

Eucalyptus sideroxylon differs by having buds that hold the outer operculum into maturity and both the inner and outer operculum shed together at anthesis (no operculum scar).

MORE ABOUT IRONBARKS

Eucalyptus melanoleuca: Greek melanos – black, leukos – white, referring to the contrasting black rough bark and white smooth bark on the branches.