Botanical description.

— Species Eucalyptus sideroxylon, A. Cunn.

Following is the earliest record I can find of this species:—

At the base of the range of hills at Mount Maude some tolerable fair specimens of the Western Ironbark, Eucalyptus sideroxylon, were noticed, being easily distinguished from its congeners by its extreme rugged, furrowed bark, containing, like others of the Eucalypti, a strong astringent gum. — (A. Cunningham's MS. Journal, under date 19th May, 1817)

Oxley's Expedition was then in latitude 33° 25' and longitude 147° 10', i.e., about midway between Condobolin and Wyalong West. Some of these specimens were distributed with Cunningham's name.

The next reference I can find is:—

6th October, 1846 (near Mount Pluto) . . . . . and among the larger forest trees was a Eucalyptus, allied to, but probably distinct from, the E. sideroxylon, A. Cunn., p. 339. — (Mitchell's Trop. Journ. Austral., 339.)

In the list of plants collected by Mitchell's Expedition, at p. 437 of his work, this plant, referred to at p. 339, is given as Eucalyptus sideroxylon without any qualification. I have seen the specimens in question, and they are what we know as Eucalyptus sideroxylon, A. Cunn.

Then Mueller described a species, under the name of Eucalyptus leucoxylon, in the following words:— "Arboreous:

Leaves. — Alternate, somewhat shining, narrow lanceolate, subfalcate, tapering into a long uncinate acumen, veined and furnished with pellucid dots; umbels axillary, generally three-flowered, with a thin peduncle.

Lid. — Conico-hemispherical, acuminate.

Tube of the calyx. — Semiovate, somewhat longer than the lid.

Fruits. — Semiovate, hardly contracted at the orifice; the valves of the capsule inclosed.

Seeds. — Blackish clathrate.

In grassy plains from the Avoca to St. Vincent's and Spencer's Gulf.

This is the "White Gum Tree" of the South Australian Colonists." — (Trans. Victorian Inst., i, 33 [1855]).

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Thereafter, for many years, this "White Gum" was confused with the New South Wales "Ironbark." For example, Bentham, in the Flora Australiensis (iii, 210), who is followed by Bailey, in the Queensland Flora. Then Mueller, in Eucalyptographia, continues to confuse the two trees. But in the field they could not be considered identical for an instant. Benthain's description of Eucalyptus leucoxylon applies very well to tbat of Eucalyptus sideroxylon, but requires to be supplemented in the following points:—

E. sideroxylon.  E. leucoxylon. 
Juvenile leaves  Linear-lanceolate or linear.  Cordate or ovate-lanceolate, sessile. 
Bark  Black, furrowed and rugged (Iron-bark)  Whitish or bluish, smooth (White or Blue Gum.) 
Timber  Deep red.  Pale brown or white (hence the name leucoxylon).