Corymbia kombolgiensis

Scarp gum

Corymbia | Blakearia

Corymbia kombolgiensis (Brooker & Dunlop) K.D.Hill & L.A.S.Johnson, Telopea 6: 414 (1995).

Eucalyptus kombolgiensis Brooker & Dunlop, Austral. Forest Res. 8: 212 (1978). T: Northern Territory: Mount Brockman, Koongarra Jump-up, 6 Dec. 1977, C.R.Dunlop 4625; holo: CANB; iso: BRI, CANB, DNA, K, NSW.

Tree to 12 m tall. Forming a lignotuber.
Bark smooth throughout, or the trunk rough, flaky to tessellated, grey for up to 3 m then becoming smooth. The smooth bark is sometimes powdery, creamy white to orange-brown.
Branchlets often have discrete, round oil glands in the pith; non-glaucous, smooth (glabrous).
Juvenile growth (coppice or field seedlings to 50 cm): stems rounded in cross-section, setose to scabrid with the remains of bristle-glands; juvenile leaves shortly petiolate, opposite, sub-opposite or alternate, ovate to elliptical, 4.5–9 cm long, 2–6 cm wide, base lobed on lowest leaves becoming rounded higher up stem, green, sparsely setose on lamina, more so on petiole.
Adult leaves opposite, sub-opposite or alternate, petioles 0.4–1.6 cm long; blade linear to narrowly lanceolate, (5.8)8–21 cm long, 0.6–1(2.5) cm wide, base tapering to petiole, margin entire, apex pointed, concolorous, glabrous, thin-textured, slightly glossy, green, side-veins usually at greater than 45° to midrib, reticulation dense to very dense, intramarginal vein present, oil glands clearly visible, island.
Inflorescence usually axillary, sometimes on (now) leafless sections of branchlet (ramiflorous), compound, the rhachis with a short basal internode (to 0.5 cm) then short and congested upper internodes, and peduncles which may be 0–1.0 cm long, strictly with the umbels in 7s but apparently up to 11s or 13s, the actual number difficult to discern because of the reduction of peduncles; buds on slender pedicels 0.5–1.5 cm long. Mature buds obovoid to pyriform, 0.4–0.6 cm long, 0.3–0.5 cm wide, smooth and glossy, scar present (outer operculum shed early), operculum shallowly rounded, stamens inflexed, all fertile, anthers oblong, dorsifixed, versatile, dehiscing by longitudinal slits, style long and straight, stigma ± blunt, locules 3 or 4, ovules not arranged in clear rows on the placentae. Flowers white.
Fruit pedicellate (pedicels 0.6–1.5 cm long), cylindrical to barrel-shaped, 0.8–1 cm long, 0.4–0.8(1.0) cm wide, thin-walled, disc descending vertically, valves 3 or 4, enclosed.
Seeds reddish brown, saucer-shaped, 3–5 mm diameter, smooth, hilum ventral.

Cultivated seedlings (measured at ca node 10): cotyledons reniform, stems rounded in cross-section, densely setose with fine, long bristle-glands; leaves always shortly petiolate, opposite, ovate to elliptical, 8–10.3 cm long, 2–4 cm wide, base rounded or tapering to petiole, margin entire, apex bluntly pointed, green, setose especially on midrib and margin.

Flowering has been recorded in August, October and November.

A small ghost gum tree endemic to the Top End of the Northern Territory, where it is restricted to sandstone escarpments and plateaus in the area from Litchfield and Pine Creek east through Arnhem Land to the coastal Bickerton Island and islands of the Sir Edward Pellew group in the western and south-western Gulf of Carpentaria respectively; and possibly also extending to the Wessel Islands.Corymbia kombolgiensis often has some rough scrappily tessellated bark on the lower trunk with most of the trunk and branches smooth, a crown of semi-glossy narrow lanceolate green leaves with oil glands easily visible when fresh. The buds are arranged in congested inflorescences with peduncles 0–1 cm long, slender pedicels 0.5–1.5 cm long, whilst fruit are thin-walled, ± cylindrical, and up to 1 cm long and 0.8 cm diameter.

Of the other ghost gum species in the general area C. kombolgiensis differs from C. polysciada in the generally narrower crown leaves, shorter peduncles and shorter pedicels of buds and fruits (though with some overlap in dimensions), whilst the rough bark of the latter species is clearly tessellated and may cover part or most of the trunk. In addition, C. polysciada also has a different habitat, seeming to prefer a zone of gravelly soils between rocky hills and adjacent plains. Other partly rough-barked ghost gums species in this area are C. confertiflora and C. disjuncta, both of which have broader, rough, setose crown leaves. Smooth-barked ghost gums in this area are essentially lowland species: C. bella and C. arafurica, both with expanded axillary inflorescences, and C. grandifolia (subspecies grandifolia and longa) which have much larger, more coarsely textured, glossy green crown leaves and strongly pedicellate buds and fruit.

MORE ABOUT CORYMBIA
MORE ABOUT GHOST GUMS

Corymbia kombolgiensis: after the Kombolgie series of sandstone beds in the Arnhem Land area of the Northern Territory where the species is abundant.