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Eucalyptus globulus subsp. bicostata


Southern blue gum, Eurabbie, Blue gum, Victorian blue gum

Eucalyptus globulus subsp. bicostata (Maiden, Blakely & J.Simm.) J.B. Kirkp., Bot. J. Linn. Soc. 69: 1010 (1975).

T: cultivated in Paris, France.

E. globulus var. bicostata (Maiden, Blakely & J.Simm.) Ewart, Fl. Victoria 804 (1931); E. bicostata Maiden, Blakely & J.Simm. in J.Simmonds, Trees Shelter & Timber New Zealand, Eucalypt 133, t. 48 (1929). T: Mundaroo State Forest, Tumbarumba, N.S.W., July 1921, W.A.W. de Beuzeville s.n.; holo: NSW.


Tree to 45 m tall. Forming a lignotuber.
Bark smooth apart from base which has persistent slabs, shedding in large strips and slabs; smooth bark white, cream, grey, yellowish or pale creamy orange, often with ribbons of decorticated bark in the upper branches.
Juvenile growth (coppice or field seedlings to 50 cm): stem square in cross-section and prominently winged, glaucous; juvenile leaves opposite and sessile for many pairs, oblong to elliptical then ovate or broadly lanceolate, 4-10.5 cm long, 2.2-5 cm wide, base amplexicaul, margin sometimes crenulate, usually discolorous with upper surface green or slightly glaucous and the lower surface copiously white-waxy.
Adult leaves alternate, petiole 3-6 cm long; blade lanceolate to falcate, 14-40 cm long, 2-6 cm wide, base usually to tapering to petiole, glossy, side-veins greater than 45° to midrib, densely reticulate, intramarginal vein well removed from margin, oil glands island and intersectional.
Inflorescences axillary unbranched, peduncle usually short and stout, 0.1-0.3 cm long; buds 3, usually sessile, hypanthium obconical, glaucous, warty, with 2 longitudinal ribs, scar present, operculum flattened and umbonate, stamens inflexed, anthers cuboid to oblong, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, stigma blunt or tapered, locules 4 or 5, the placentae each with 6(8) vertical ovule rows; flowers white.
Fruit sessile, hemispherical to obconical, 1-2 cm wide, 2-ribbed longitudinally, glaucous or non-glaucous, disc raised-convex and lobed over the 4 or 5 valves which are usually near rim level.
Seed black, brown or grey, 1.5-3 mm long, ovoid to flattened-ovoid or slightly cuboid, often lacunose, dorsal surface shallowly pitted, hilum ventral.

Cultivated seedlings (measured at ca node 10): ): cotyledons bilobed; stems squared in cross-section and prominently winged also, glaucous; leaves sessile, opposite for many nodes, oblong to ovate or elliptical, 4-11 cm long, 2.5-5 cm wide, amplexicaul, margin entire or subcrenulate, apex pointed, glaucous to blue.


NOTES

Eucalyptus globulus (Latin globulus, a globe, a ball, refers to the fruit shape).
E. globulus is a forest tree species that is widespread in the ranges and subcoastal forests of southern New South Wales, eastern Victoria and Tasmania. It is notable for the very conspicuous seedlings, coppice and young saplings with square stems and large, glaucous, oblong to ovate sessile juvenile leaves. The trunks are mostly smooth and the adult leaves are large, bright glossy green and usually falcate.

There are 4 subspecies:

subsp. globulus
Of largely lowland distribution in Tasmania and central-south, coastal and subcoastal distribution in Victoria. It has a single, large, sessile, glaucous, warty bud per axil (rarely in 3s).

subsp. bicostata (Latin bicostatus, two-ribbed, of the fruit).
A montane and tableland subspecies in southern New South Wales and Victoria mostly on the northern slopes of the Great Dividing Range west to the Pyrenees, and with a single population in South Australia on Mt Bryan north of Burra. It has similar sessile buds to subsp. globulus but they are slightly smaller and occur in 3s.

subsp. pseudoglobulus (Latin pseudo-, false and globulus, refers to its resemblance to E. globulus ).
From the coastal ranges in east Gippsland but with inland populations at Lerderderg Gorge and north of Toongabbie. It is close to subsp. bicostata but has stoutly pedicellate buds in 3s.

subsp. maidenii (after Joseph Henry Maiden, 1859-1925. In 1881 Maiden was appointed first curator at the Technological Museum Sydney, where he remained until 1896. In the same year he was appointed Government Botanist of New South Wales and Director of the Botanic Gardens, Sydney, where he remained until 1924. When Maiden took over this position, the state had no herbarium, no collection of local flora, no museum and no library of botanical works, a situation he quickly rectified. Maiden is one of the great names in the study of Eucalyptus. He is the author of the monumental eight volume publication, A Critical Revision of the Genus Eucalyptus).
Occurs in subcoastal ranges of far south-eastern New South Wales and far eastern Victoria and has smaller, pedicellate buds in 7s, often not glaucous, but still with the warty, umbonate operculum typical of the group.

Intergradation commonly occurs between subspp. globulus, bicostata and pseudoglobulus where they come into contact and with populations in southern Victoria it may be impossible to attribute a specimen to any particular subspecies. Also the natural distribution of subsp. globulus in Victorian and Tasmanian forests has undoubtedly been confused by forestry plantings in the twentieth century.

Eucalyptus globulus belongs in Eucalyptus subgenus Symphyomyrtus section Maidenaria, a large group of species more or less restricted to south-eastern Australia, characterized by bilobed cotyledons, simple axillary inflorescences, buds with two opercula, stamens with versatile anthers and flattened seeds with a ventral hilum. Within this section, E. globulus belongs in series Globulares subseries Euglobulares, having large, sessile, glaucous, juvenile leaves opposite for many pairs on square, winged stems, buds solitary or in clusters of 3 or 7 and fruit with prominent disc partly covering valves.

USES

Eucalyptus globulus is a widely used species in pulp and timber production and has been the subject of much forestry research.
E. globulus subsp. bicostata is widely planted as an ornamental in southern Australia and overseas.