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Eucalyptus aggregata

Black gum

Eucalyptus aggregata Deane & Maiden, Proc. Linn. Soc. New South Wales 24: 614 (1900).

T: Wallerawang, N.S.W., Nov. 1899, J.H. Maiden s.n.; lecto: NSW, fide J.H.Maiden, Crit. Revis. Eucalyptus 3: 100 (1915); isolecto: K.

E. rydalensis R.Baker & H.G.Smith, Res. Eucalypts 2nd ed., 48 (1920). T: Rydal, N.S.W., Oct, 1909, ?C.Laseron s.n.; herbarium of cited specimen not known to us.

Tree to 20 m tall. Forming a lignotuber.
Bark rough throughout or branches <8 cm diameter smooth, rough bark flaky and fissured or fibrous, dark grey to grey-brown.
Juvenile growth (coppice or field seedlings to 50 cm):
stem rounded in cross-section; juvenile leaves opposite at first but soon alternate, petiolate, ovate to elliptical or lanceolate, 4-7 cm long, 1.5-3 cm wide, margin entire or crenulate, green. Juvenile leaf shape may vary considerably in a single seedlot.
Adult leaves alternate, petioles 0.4-1.5 cm long
; blade lanceolate, 5-12 cm long, 1-2.5 cm wide, slightly glossy or dull, side-veins at an acute or wider angle to midrib, moderately to densely reticulate, intramarginal vein parallel to and just within margin or well removed from it (sometimes double), oil glands mostly island.
Inflorescences axillary unbranched, peduncles 0.1-0.5 cm long; buds 7, pedicellate or sessile, ovoid, green to yellow, scar present, operculum conical, stamens inflexed or irregularly flexed, anthers cuboid to oblong, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, locules 3 or 4, each with 4 vertical ovule rows; flowers white or cream.
Fruit obconical, 0.3-0.5 cm wide, disc slightly raised or level, valves 3 or 4, strongly exserted or near rim level.
Seed brown-grey, 1.2-2 mm long, ovoid or flattened-ovoid, often pointed at one end, sometimes lacunose, dorsal surface smooth, hilum ventral.

Cultivated seedlings (measured at ca node 10): cotyledons bilobed to oblong; stems rounded in cross-section, warty or smooth; leaves sessile or shortly petiolate, opposite for 4 or 5 nodes then subopposite to alternate, variable in shape but usually ovate-elliptical, 3-6 cm long, 0.6-3.7 cm wide, base tapering, rounded or amplexicaul, green to grey-green.


Eucalyptus aggregata (Latin aggregatus, clustered together, of the fruits).

A small to medium-sized tree belonging to the small-fruited swamp gums, it is completely rough-barked and has very small ovoid buds and obconical fruit. It occurs from Cox's River north of Lithgow on the west-central tablelands to the southern tablelands of New South Wales and there is a small occurrence near Woodend in central Victoria. The habitat is invariably hollows and swamps where there may also occur E. ovata which is easily distinguished by the larger leaves that are undulate. E. yarraensis is another rough-barked swamp gum, endemic to Victoria, which is similar to E. ovata in leaves, buds and fruits and is therefore morphologically distinct from E. aggregata. The Tasmanian endemic related species E. rodwayi is a taller erect tree which has conspicuous, large, glossy green, pendulous juvenile leaves.

Eucalyptus aggregata belongs in Eucalyptus subgenus Symphyomyrtus section Maidenaria because the cotyledons are bilobed, inflorescences axillary, anthers versatile and seeds flattened-ovoid. Within this large section, E. aggregata is one of ten species forming series Foveolatae further characterized by being swamp-dwellers with fruit ± obconical.