Swamp Gum

Systematic. - A medium-sized tree reaching a height of 40-50 feet and a diameter of 18 inches; with a thick and spongy, rough decorticating bark, extending well up the tree. Abnormal leaves shortly petiolate or sessile, ovate to broad-lanceolate, opposite or alternate. Normal leaves lanceolate to broad-lanceolate, more or less shining, acute, usually under 3 inches long; venation fairly distinct in the older leaves, intramarginal vein well removed from the edge, lateral veins distant, roughly parallel, inclined at an angle of 30°-40° with the mid-rib. Oil glands more prominent in the young leaves. Peduncles short, 1 to 2 lines long, axillary, lateral or in short terminal panicles, each bearing a head of about seven flowers. Buds sessile or almost so, calyx tube turbinate, 1 line in length; operculum hemispherical, half as long as the tube.

Fruit. - Broad, turbinate to hemispherical, sessile, more or less shining; rim domed; valves broad and short, exserted; 2 lines long and 2 1/2 lines in diameter.

The fruit rather closely resemble those of E. Macarthuri than any other, the slightly rounded rim being perhaps the chief difference.

Habitat. - Rydal, New South Wales.

REMARKS.-This is a rare Swamp Eucalyptus as far as is known to us. Mr. Laseron, the Museum Collector, states that he only saw three trees near Rydal, New South Wales. The bark is thick and spongy, but rougher very much higher up than that of E. viminalis growing in juxtaposition. It differs, however, very materially from that species in physical characters and chemical constituents, amongst the former may be mentioned the inflorescence, fruits and both forms of leaves. The timber appears to be very inferior. The herbarium material has the fades somewhat of E. Macarthuri, but the specific aroma of the latter at once differentiates the two. The buds are not unlike those of E. maculosa, but that is the only connection with that species. The fruits which come closest to them in shape are E. Macarthuri more particularly, and next, perhaps, E. angophoroides and E. Bridgcsiana, but these are both of a larger size, and trees with a " Box " bark. The abnormal leaves and chemical constituents of the oil are the principal features by which it can be distinguished from its nearest affinity, E. Macarthuri.

ESSENTIAL OIL. Leaves and terminal branchlets for distillation were received from Rydal, N.S.W., in October, 1909. The yield of oil was 0.26 per cent.

The crude oil was of a light amber colour, and had a terpene-like odour with little resemblance to ordinary Eucalyptus oil. It consisted principally of dextro-rotatory pinene, together with the sesquiterpene. Phellandrene was not detected, and cineol was only present in very small amount. Esters occur in some quantity, the principal one being geranyl-acetate.

The oil of this species has a strong resemblance to that of E. acacici'jormis. The crude oil had specific gravity at 150 C. = 0.8854; rotation aD + 24.7° ; refractive index at 200 = 1.4717, and was insoluble in 10 volumes 80 per cent. alcohol. The saponification number for the esters and free acid was 44, while in the cold with two hours' contact it was 36. The secondary odour of the cold saponified oil suggested geraniol.

On rectification 1 per cent. distilled below 1570 C. (corr.). Between 157-1720, 62 per cent. distilled; between 172-194°, 10 per cent. came over, and between 194-2760, 20 per cent. distilled. These fractions gave the following results: -

The cineol was determined by the resorcmoi method in the portion distilling below 1940. When calculated for the crude oil the result was 8 per cent.