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No. 177: Acacia obtusata,

Sieb.,

var. Hamiltoni, Maiden.

Hamilton's Wattle.

(Family LEGUMINOSÆ: MIMOSEÆ.)

*

This plant is identical with Sieber's No. 464, and I have already referred to it when speaking of A. adunca, A. Cunn., in Part XLVI of the present work.

At the risk of some repetition I again give quotations in which Sieber's No. 464 is referred to:—

Then we have "A. Crassiuscula, Wendl.," described in B.Fl. ii, 372 (1864). Bentham repeats this in Trans. Linn. Soc., xxx, 473.

This is in part Sieber's No. 464, as stated by him, but it includes Queensland and Tasmanian plants, of whose identity I am in doubt, at present, as I have been unable to obtain satisfactory specimens.

I will show later that Sieber's No. 464 is A. obtusata, Sieber, var. Hamiltoni, var. nov., which I will figure and describe in Part XLVIII of this work. (A promise carried out in the present Part).

Then Bentham (B.Fl. ii, 368) (1864) gives A. crassiuscula, Meissn., in Pl. Preiss. i, 16 (not of Sieber) as a synonym of A. pycnophylla, Benth. He repeats this in Trans. Linn.Soc., xxx, 471 (1875). Meissner's specimen was collected near Albany, W.A. (Princess Royal Harbour.)

So that we have —

(1) A. crassiuscula, Wendl. This is A. pycnophylla, Benth.

(2) A. crassiuscula, Meissner. This is A. pycnophylla, Benth., also (as, indeed, stated by Bentham).

(3) A. crassiuscula, Sieber. His No. 464. This is, I repeat, A. obtusala, Sieber, var. Hamiltoni, Maiden.

I am indebted to Colonel Prain, Director of Kew, for giving permission to Miss Smith to figure the Kew specimen of Sieber's No. 464, which has been lithgraphed by Miss Flockton on Plate No. 181, and also for some small specimens of the plant itself, I cannot separate it from A. oblusata, Sieb., although the two plants look different enough at first sight.

It may be described in the following words:—

An erect, busby shrub of 5 or 6 feet, quite glabrous, exhibiting a bluish-green cast when growing, branchlets angular.

Phyllodia lanceolate, straight or a little curved, sometimes tending to be spathulate, terminating in a fine point, the end of the phyllode sometimes bent obliquely, usually 1 1/2 to 1 3/4 inch long, rigidly coriaceous, one nerved, with thickened nerve-like margins, the veinlets inconspicuous, with or without marginal glands, the gland when present being about one-fifth of the way up from the base.




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Racemes not exceeding or equalling the phyllodes, with numerous heads of about twenty flowers, all 5-merous.

Sepals thick, spathulate, angled, fringed at the top and along the angles with fine hairs, half as long as the corolla. Petals glabrous. Ovary smooth.

Pod 1/4 inch broad, the valves with a raised rim along the margin, the pod contracted between the seeds, which are longitudinally arranged.

Seed with a club-shaped aril and a funicle short or as long as the seed, but not encircling it.

Mr. R. T. Baker, Proc. Linn. Soc. N.S.W., xxii, Plate xxiii, has figured Acacia obtusata, Sieber, and at figure 2 has figured "Flowering twig of variety with small phyllodes." This twig came from Tallong (Barber's Creek) (H. J. Rumsey), and is reminiscent of var. Hamiltoni, but the phyllodes are more attenuate-spathulate than the type, have the gland usually more distant from the articulation of the phyllode, and the gland usually more prominent.

With this exception, I have not found a, form similar to var. Hamiltoni in southern New South Wales.

Botanical Name.

— Acacia, already explained (see Part XV, p. 104); Hamiltoni, in honour of Arthur Andrew Hamilton, Botanical Assistant, Botanic Gardens, who found this plant at Leura, Blue Mountains.

Vernacular Name.- I know of none in actual use, and propose the name "Hamilton's Wattle" for it.

Synonym.

— A. crassiuscula, Benth. non Wendl. in part.

Habitat.

— Leura, Blue Mountains, New South Wales. So far as I know this is the only locality in which this Acacia has been collected since Sieber's time, Mr. A. A. Hamilton having obtained it in fruit in December, 1907, and in flower in September, 1908.

I collected an Acacia at Mount Wilson in April, 1896, which is in young bud and doubtful, but which appears to be this form.

Tallong, between Moss Vale and Goulburn, is a southern form, and I expect this variety to be obtained in the rough country connecting the southern line and the western line (Blue Mountains).

EXPLANATION OF PLATE 181.

Plate 181: Hamilton's Wattle. (Acacia obtusata, Sieb., var. Hamiltoni, Maiden.) Lithograph by Margaret Flockton.



  • A. Flowering twig.
  • B. Flower-head.
  • C. Individual bud.
  • D. Flower.
  • E. Bract.
  • F. Flower opened out, showing —
    • (a) Calyx.
    • (b) Corolla.
    • (c) Pistil (stamens removed).
  • G. Phyllode enlarged, showing gland (a).
  • H. Pod.
  • I. Seed.

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