Coolibah

Description

Eucalyptus microtheca, commonly known as the coolibah, is a species of tree that is endemic to northern Australia. It has rough, flaky or fibrous bark on the trunk and branches, lance-shaped adult leaves, flower buds in groups of seven, white flowers and spherical to conical fruit. It is widely distributed from the Kimberley region of Western Australia to Cape York in Queensland. Eucalyptus microtheca is a tree, sometimes a mallee, that typically grows to a height of 5–10 m (16–33 ft) and forms a lignotuber. It has a whitish grey to dark grey, box-type bark that is often deeply fissured, coarsely flaky or tessellated as it ages. Young plants and coppice regrowth have narrow lance-shaped leaves that are 50–150 mm (2.0–5.9 in) long, 5–25 mm (0.20–0.98 in) wide and petiolate. Adult plants have leaves that are the same shade of dull green to bluish on both sides, lance-shaped to curved, 50–195 mm (2.0–7.7 in) long and 6–30 mm (0.24–1.18 in) wide, tapering to a petiole 6–20 mm (0.24–0.79 in) long. The flower buds are arranged on a thin, branched peduncle in groups of seven, the peduncle 2–9 mm (0.079–0.354 in) long, the individual buds on pedicels 1–3 mm (0.039–0.118 in) long. Mature buds are pear-shaped to oval or spherical, 3–4 mm (0.12–0.16 in) long and 2–3 mm (0.079–0.118 in) wide with a rounded operculum with a point in the centre. Flowering occurs between September and January and the flowers are white. The fruit is a woody, shortened spherical or conical capsule 2–5 mm (0.079–0.197 in) long and 3–7 mm (0.12–0.28 in) wide with the valves near rim level. The tree is distributed widely across northern Australia and mostly found along river banks and in the heavy soils of flood plains. It is the second most widely distributed species in Australia after Eucalyptus camaldulensis. The species is found waterlogged flats, along the margins of swamps in the Kimberley region of Western Australia. Populations of the tree are scattered through several IBRA regions including Dampierland, Northern Kimberley, Central Kimberley, Ord Victoria plain and Victoria Bonaparte. It is also distributed throughout the top end of the Northern Territory east from the Western Australian border as far north as about Newcastle Waters and through the Barkly Tableland east through the catchment areas of the Roper and McArthur Rivers and into the Gulf Country of Queensland.