Eucalyptus globulus subsp. bicostata (Maiden, Blakely & Simmonds) J.B.Kirkp.

Eucalyptus bicostata Maiden, Blakely & Simmonds

blue gum, eurabbie, southern blue gum, Victorian blue gum

Australia: eastern New South Wales and in Victoria, mostly on the slopes of the Great Dividing Range, and a single old population in South Australia on Mt Bryan.

In New Zealand occasionally cultivated in parks, as shelter or in forestry plantations; records of naturalisation from nearby specimens extremely rare.

Scattered records from throughout New Zealand, particularly from Hawkes Bay to Canterbury.

• A tree to 45 m tall with bark smooth apart from base which has persistent slabs of rough bark, shedding in large strips and slabs; smooth bark white, cream, grey, yellowish or pale creamy orange, often with ribbons of shed bark in the upper branches.
• Young stems flanged and square in cross-section; waxy grey-white saplings and coppice very conspicuous.
• Long, glossy, green, adult leaves to 400 mm long and 60 mm wide, alternate, stalked, lanceolate to sickle-shaped.
• Juvenile leaves that are opposite and stalkless for many pairs, broadly elliptic to ovate to broadly lanceolate, to 115 mm long and 60 mm wide, base stem-clasping, margin sometimes scalloped, usually upper surface green or slightly waxy grey-white and the lower surface copiously white-waxy.
• Flowers in clusters of 3, in leaf axils; mature buds are stalkless or short-stalked, green, bud cap flattened with a central, raised knob, flowers white.
• Fruit a stalkless woody capsule, rounded or funnel-shaped, usually to 10 mm long and 22 mm wide, 2-ribbed longitudinally, may be waxy grey-white, disc raised above the rim and lobed over the 4 or 5 valves which are usually near rim level.

Tree to 45 m tall.

Bark smooth apart from base which has persistent slabs of rough bark, shedding in large strips and slabs; smooth bark white, cream, grey, yellowish or pale creamy orange, often with ribbons of shed bark in the upper branches. Hairs and adventitious roots absent. Young stems square in cross-section, and prominently winged, waxy grey-white.

Adult leaves alternate, stalked, blade lanceolate to sickle-shaped, 140–400 mm long, 20–60 mm wide, base usually tapering to stalk, glossy, same colour above and below, hairless; side-veins at an angle greater than 45° to midrib, vein reticulation dense, intramarginal vein parallel to and well removed from margin, oil glands present; leaf stalk 20–35 mm long.

Juvenile leaves opposite and stalkless for many pairs, oblong to elliptic then ovate to broadly lanceolate, (30–)40–115 mm long, (17–)22–60 mm wide, base stem-clasping, margin sometimes scalloped, usually different colour above and below with upper surface green or slightly waxy grey-white and the lower surface copiously white-waxy.

Flowers in clusters of 3, in leaf axils, stalk of cluster usually short and stout, 1–3 mm long; buds free, usually stalkless, (rarely central bud with stalk to 2 mm). Base of mature bud funnel-shaped, waxy grey-white, 10–18 mm long, 10–14 mm wide, with 2 longitudinal ribs; bud cap flattened with a central, raised conical tip, flowers (stamens) white; in mature open flowers, petals and sepals absent. Main flowering period: summer to autumn.

Capsules woody, stalkless, rounded or funnel-shaped, 7–10(–17) mm long, (10–)13–22 mm wide, 2-ribbed longitudinally, may be waxy grey-white, disc raised above the rim and lobed over the 4 or 5 valves which are usually near rim level.

The four subspecies of E. globulus have very similar bark, adult and juvenile foliage; buds usually with a warty, waxy-white, flattened cap with central knob; woody capsules varying from rounded to funnel-shaped; but they differ in number of buds or capsules in a cluster, and the size of buds and capsules.

• Eucalyptus globulus subsp. globulus usually has large, solitary, warty buds or capsules, but very occasionally they are in 3s. Capsules to 21 mm long, to 27 mm wide.
• Eucalyptus globulus subsp. bicostata and E. globulus subsp. pseudoglobulus have buds in 3s, but the former has sessile buds that are waxy grey-white, and a very short cluster stalk, with capsules to 22 mm wide, whereas the latter usually has the central bud on a short stalk, buds are often strongly ribbed, may or may not be waxy grey-white, the stalk of the cluster is broad and flattened, to 10 mm long and capsules are smaller, to 16 mm wide.
• Eucalyptus globulus subsp. maidenii has smaller, stalked buds in clusters of 7 that may or may not be waxy grey-white, the stalk of the cluster is flattened and long, to 25 mm, and smaller capsules to 10 mm wide.

Eucalyptus globulus is a forest tree species that is widespread in the ranges and subcoastal forests of eastern New South Wales, eastern, southern and central Victoria, and Tasmania. It is notable for the very conspicuous seedlings, coppice and young saplings with square stems and large, waxy grey-white, oblong to ovate, stalkless juvenile leaves. The trunks are mostly smooth and the adult leaves are large, bright glossy green and usually sickle-shaped.

Intergradation commonly occurs between E. globulus subsp. globulus, E. globulus subsp. bicostata and E. globulus subsp. pseudoglobulus where they come into contact, and with populations in southern Victoria it may be impossible to attribute a specimen to any particular subspecies.

Eucalyptus is a genus of nearly 800 species, most of which are endemic to Australia, with a few species extending to parts of Malesia and as far north as the Philippines.

• EUCLID
• Flora of Australia
• GBIF
• iNaturalist NZ
• PlantNET: New South Wales Flora Online
• Plants of South Eastern New South Wales
• VicFlora: Flora of Victoria