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No. 229: Acacia Mabellæ

Maiden.

Mabel's Wattle.

(Family LEGUMINOSÆ MIMOSEÆ.)

Botanical description.

— Genus, Acacia. (See Part XV, p. 103).

Botanical description.

— Species, Mabelæ Maiden, in Proc. Roy. Soc. N.S.W. xlix, 475 (1915).

Arbor umbrosa mediocriter alta, trunco usque ad 1' diametro, surculis junioribus et rhachibus inflorescentiæ brevibus pilis aureis tectis. Phyllodiis longis angusto-lanceolatis apice obtuso, ad 30 cm. longis et longioribus, circa 1 cm. latis. Nervis mediis marginalibusque prominentibus, lateralibris obscurissimis. Glandula non conspicua basi 1 cm. remota. Inflorescentia racemosa, capitulis circa 9 — 13 floris. Calyce corollae aequilonga, calyce truncata vel fere truncata. Sepalorum apicibus pubescentibus, petalis glabris, pistillo laeve. Legumine longiusculo latiusculoque (circa 13 x 1 cm.) subfalcato, seminibus longitudinaliter dispositis; seminis filiforme funiculo semen bis circumcingente, in clavatum arillum apice seminis terminante. Species A. retinodes Schlecht, proxima videtur.

An umbrageous tree of moderate height (up to 30 feet), with a trunk diameter up to a foot. Branchlets angular. The young shoots and the rhachises of the inflorescence densely covered with short, golden-yellow hairs. The bark of young growing trees is usually glaucous.

Seedling. — The seedling will be described by Mr. R. H. Cambage in his papers on Acacia seedlings, but its differences from that of A. penninervis and A. rubida may be briefly stated in the following words: the young phyllodes of A. Mabellæ are longer and much narrower than those of the other two species, and the venation is quite distinct from either.

Phyllodes. — Long narrow-lanceolate and slightly falcate. Up to 20 cm. and even longer. Width for the greater portion of the length about 1 cm. Rather thin in texture, blunt-pointed. Mid- and marginal-veins prominent, the lateral veins very faint, though visible under a lens, spreading. A not very conspicuous gland about 1 cm. from the base, the margin of which is slightly kinked at the place of the gland, and from which a rudimentary oblique vein sometimes proceeds. No stipules observed. Inflorescence racemose, the flowers borne in profusion, of a pale yellow colour, and sweet-scented.

Flowers about nine to thirteen in the head, pentamerous, calyx and corolla of about equal length, calyx truncate or nearly so, glabrous except for the tips of the sepals, which are tufted with hairs. Petals glabrous, slightly keeled, the tips a little thickened. Pistil smooth.

Pod moderately long and broad, (say 13 x 1 cm.), slightly curved. Margins of the valves thickened and somewhat grooved, the valves more or less wrinkled, the seeds arranged longitudinally, distending the valves without making the pods moniliform.

Seed with filiform funicle twice encircling it, and terminating In a clavate arillus at the top of the seed. The length and contour (whether kinked or not) of the funicle is subject to variation, as in A. rubida.

Affinities.

— This wattle belongs to the series Uninerves and the long sub. series Racemosæ Because of the general similarity of the structure of the flowers, Acacia Mabellæ has hitherto been assumed to be a form of A. penninervis; the seed and seedling show that it is not closely related to that species. From the point of view of the seed, with its encircling funicle, its affinity must be sought for near A. retinodes Schlecht., and A. rubida A. Cunn.

1. With A. retinodes Schlecht.

The phyllodes of the new species are longer, the marginal veins more marked, and the lateral veins different. The lateral veins in A. retinodes (a Victorian and South Australian species) are more or less parallel to the mid-rib; in A. Mabellæ they are attached to the mid-rib at an acute angle.

The flowers of the new species are fewer in the head and are more squat than those of A. retinodes, which also have the tips of the petals recurved and the pedicels glabrous. The rhachises of the inflorescence are without the golden yellow pubescence to be seen in A. Mabellæ.

The pods of A. retinodes are narrower, but the funicles are not dissimilar.

The two species bear, however, such general and detailed resemblance to each other that it is obvious that they are closely related. At the same time I am satisfied that the species are sufficiently distinct from each other.

2. With A. rubida A. Cunn.

A. Mabellæ resembles it in seedlings and encircling funicle to the seed only. The phyllodes of A. rubida are much coarser, of a different colour, and they generally have a fine more or less hooked tip. They have not the pendulous appearance of A. Mabellæ, neither is the persistent bipinnate foliage of A. rubida so obvious. The stems and rhachis of A. rubida are waxy smooth except at the extreme tips, which have a yellow pubescence.

The flowers also of A. rubida are of a rich golden yellow, while in the new species they are of a pale whitish cream colour, and the rhachis matted with hair.

3. With A. penninervis Sieb.

The rhachis of the new species is densely clothed with a golden pubescence; it is smooth in A. penninervis, though there is a tomentum of a similar character (though less copious), in the variety falciformis of A. penninervis.

The venation of the phyllodes is indistinct, but similar to that of A. penninervis; there is no intramarginal vein, but the edges of the phyllodes are nerve-like and the mid-rib prominent on both sides. There is a gland as in A. penninervis. The phyllodes are much longer than those of A. penninervis.

As regards the new species, the flowers are cream-coloured and sweet scented; those of A. penninervis have less odour. The petals are five or six in number, glabrous, broader than those of A. penninervis, and much more frail in texture.

The seeds of the new species have a double funicle completely surrounding them; those of A. penninervis have a shorter funicle. Bentham (B. Fl. ii, 362) says, "funicle long, dilated and coloured nearly from the base, extending round the seed and bent back on the same side, so as to encircle it in a double fold."

I have not been able to confirm Bentham's observations in this respect. In the specimens belonging to the typical form that I have been able to examine, the funicle has hardly extended half round the seed. In var.falciformis I have observed funicles that I cannot distinguish from those of the normal form and in addition, doubly folded funicles extending more than half way round the seed, but never doubly encircling funicles as in A. Mabellæ.

The seedlings of the two species may be briefly contrasted as follows:— the phyllodes of the former are shorter and very much broader and have a distinct venation.




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Synonym.

— A. penninervis Sieb., var. angustifolia Maiden in "Wattles and Wattle- barks," 3rd Edition, p. 49 (1906). It was described in the following words:—

A long narrow-phyllode form, found only on the South Coast, so far as I know. Phyllodes commonly six inches long, and under half an inch wide, straight or slightly falcate. The pods are narrower than in the normal form. The young shoots and the rhachises of the inflorescence are sometimes densely covered with golden yellow hairs.

Botanical Name.

— Acacia, already explained (see Part XV, p. 104); Mabellæ, "I constitute the Milton specimens type of the new species, which is named in honour of my young friend, Miss Mabel Fanny Cambage. The naming of a wattle after her is appropriate, because she is Honorary Treasurer of the New South Wales Branch of the Wattle Day League, in connection with which she has done admirable service, and this particular wattle has associations for her in that many specimens occur on the South Coast property of her grandparents."

Vernacular Name.

— To a limited extent it shares the name "Black Wattle" with other species on the South Coast, and in New South Wales generally "Mabel's Wattle" is a distinctive and appropriate name.

Bark.

— Bark from Nelligen, stripped in December, gave 32.25 per cent. of tannic acid, and 52.8 per cent. of extract; while a specimen from the Dromedary, much further south, gave an almost identical result, viz., 32 per cent. of tannic acid and 52.7 per cent. of extract.

Timber.

— So far as I am aware, this timber is not used for any constructive purposes (other than rough uses), but in common with some other wattles it is a good baker's fuel.

Habitat.

— Twelve to 20 feet high, Mogo about eight miles from Bateman's Bay township (W. Baeuerlen, September, 1890). Bateman's Bay (J.H.M., November, 1892). Conjola (W. Heron, September, 1898, and February, 1899).

"Black Wattle." Tree good for tan bark. Up, to about 30 feet high. Milton (R. H. Cambage, No. 784, December 1902. No. 4,113; November, 1914; No. 4,151, August, 1915). Nelligen road, 71 miles from Braidwood (R. H. Cambage, No. 2,065).

Mr. Cambage informs me that in going south from Nowra, the Black Wattle is first met with by the roadside at about 17 miles north of Milton. Around Milton this species avoids the most basic soils, and grows on a sandy soil which is mixed with a better soil, but does not occur on the poor, highly siliceous Permo-Carboniferous formation.

Mr. W. Dunn records it from Bermagui as a tree of 50 feet. It is confined to New South Wales, and mainly a South Coast species. Its range requires to be more fully ascertained.

EXPLANATION OF PLATE 234.

Plate 234: Mabel's Wattle. (Acacia Mabellae, Maiden.) Lithograph by Margaret Flockton.



  • A. Flowering twig from Milton, N.S.W.
  • B. Flower-head.
  • C. Flower, stamens not shown.
  • D. Pistil.
  • E. Floral bract.
  • F. Pod.
  • G. Seed.

PHOTOGRAPHIC ILLUSTRATION.

For a photograph of the tree, see Part 50 of this work.

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