In addition to being the largest and most durable timber of the country, the gum-trees yield a variety of useful products. Most of them exude a valuable gum resin; the bark of others is employed in tanning, and the oil of Eucalyptus is now extracted to the extent of 2000 gallons annually in one factory. Several of them periodically shed their barks in large sheets, after the manner of our planes and birches, but more thoroughly. The leaves, like those of many other Australian trees, are vertical instead of horizontal, so that they afford comparatively little shade. Unlike our forest trees, too, they have more or less conspicuous flowers—some of the western species especially large and highly coloured flowers, followed by woody seed-vessels varying in different species from less than a quarter of an inch to three inches in diameter, and containing numerous very small seeds.
The genus Eucalyptus belongs to a tribe of the Myrtaceæ characterised by having a dry instead of a fleshy fruit. To the same group belongs the large genus Melaleuca, which is likewise almost peculiar to Australia and spread all over it. Conspicuous among the species of Melaleuca is M. Leucadendron, which inhabits all except the south-eastern region. It is called tea-tree, paper-bark tree, and milkwood in the different colonies. The wood of this tree is very beautiful and durable, and valuable for shipbuilding and other purposes; and the papery bark is said to be impervious to water and remains sound after the wood has decayed. The accompanying woodcut (p. [373]) will give an idea of the aspect of the tree.
Next to the Eucalypti, the Proteaceæ and Acaciæ are almost everywhere prominent features in the landscape. The numerous species of Banksia, honeysuckles of the colonists, are generally dispersed, and easily recognised by their large dense heads of showy flowers, succeeded by large, gaping, woody seed-vessels.
With few exceptions, the species of Acacia differ from those of other parts of the world (except two or three in the Mascarene and Sandwich Islands) in the feathery pinnate leaves being reduced to vertically flattened, rounded, and variously shaped organs corresponding to the leaf-stalk, and termed phyllodes. Occasionally, and especially in young seedling-plants, the ordinary pinnate blade is born at the end of the phyllode, thus giving a clue to its true nature.
AN AUSTRALIAN SPRUCE (Araucaria Bidwillii).
True cone-bearing trees are rare in Australia, but the allied slender-branched weeping species of Frenela (Callitris) and the very similar Casuarineæ (the she-oak, river oak, forest oak, etc.) are almost inseparable from Australian scenery. In Queensland and northern New South Wales there are, however, two remarkable true cone-bearing trees: namely, the bunya-bunya (Araucaria Bidwillii) and the Moreton Bay pine (A. Cunninghamii). There are other species of Araucaria in Norfolk Island, New Caledonia, and South America. The Australian species both afford a valuable timber, but it is not permitted to fell the bunya-bunya on the Crown lands, owing to its seeds being a valuable article of food to the aborigines.
THE TEA-TREE (Melaleuca Leucadenron).
Even so slight a sketch as this of the vegetation of Australia would be singularly imperfect without some reference to the highly peculiar grass-trees (Xanthorrhœa), which form so striking a feature in the scenery, especially in West Australia. The larger species have stout trunks surmounted by a tuft of long narrow recurved leaves, from the centre of which rise the tall, slender, shaft-like inflorescences.