Family

Fabaceae

Distribution

This possible new species is geographically and ecological restricted. It occurs in Northern Territory in the Petermann Range (not far from the W.A.) border and in the vicinity of Uluru National Park. A few sterile specimens from W.A. (in the vicinity of Warburton and Giles) my possibly be this species, but fertile material is need to confirm the identification. A few specimens from the same region, referred to be Maslin & Reid (2012: 171) as possible intermediates between A. aneura and A. ayersiana, need to be reassessed in relation to Acacia sp. Mulga Blue Crowns (D.E. Albrecht 9573).

Description

Trees 4–9 m tall, multi-stemmed when young but maturing single-stemmed with a straight bole to c. 30 cm dbh, crown dense and bluish in colour; readily re-sprouting from base following fire. Branchlets rather prominently resin-ribbed towards apices, the resin quite well-developed and translucent, hoary between the ribs, ribs absent or obscure and hairs absent on mature branchlets. New shoots generally not or only slightly resinous; youngest 1–3 phyllodes normally obscurely or obviously striate with silvery white or pale cream hairs between the dark-coloured, sometimes obviously resinous nerves, indumentum rarely obscuring the nerves, the marginal nerve pronounced, dark-coloured and resinous. Phyllodes narrowly elliptic, moderately to strongly recurved (juvenile phyllodes straight and dimidiate to shallowly recurved, 3–7 cm x 6–8 mm), not rigid, flat, 6–13 cm long, 4–6(–8) mm wide, apex short-acuminate, minutely and obscurely appressed-hairy between the nerves, glaucous, ashen or grey-green, parallel longitudinal numerous, uniform prominence and relatively wide, sometimes (especially young phyllodes) sub-distant; discrete marginal nerve present, sometimes not especially prominent (except youngest phyllodes), yellow to light brown or reddish brown. Gland situated on upper margin of phyllode 0–1 mm above pulvinus. Inflorescences simple; peduncles 2–4 mm long, hoary or scurfy; spikes 14–18 mm long. Flowers 5-merous; sepals free or united at base, linear-spathulate or oblong-spathulate, slightly longer than ½ length of petals. Pods narrowly oblong, 2.5–5(–6) cm long, 9–12(–15) mm wide, straight, flat scarcely constricted between seeds, thinly coriaceous, greyish brown, glabrous or sparsely and minutely appressed hairy, obscurely reticulate, margins very narrowly winged or sometimes bevel-edged (at least along one margin), wing 0.5–0.7 mm wide. Seeds unknown.

Habitat

Acacia sp. Mulga Blue Crown (D.E. Albrecht 9573) normally forms monotypic stands of normally widely spaced individuals. Grows in swales of sand dunes or (in south-eastern extremity of the Peterman Ranges) the lower slopes of small rocky (sandstone) hills. Frequent fires in the area where Acacia sp. Mulga Blue Crown (D.E. Albrecht 9573) occurs appear to often prevent surviving plants from attaining maturity and there is a possibility in the absence of effect fire management the survival of the remaining plants is precarious.

Specimens

N.T.: 33.5 km W along Docker River road from intersection with Kata-Juta – Uluru road, D.E. Albrecht 9573 (DNA, NT, PERTH); c. 68 km W along Docker River road from intersection with Kata-Juta – Uluru road, D.E. Albrecht 9583 (NT, PERTH); 50 mi [80 km] W of Ayers Rock, C. Dunlop 1951 (NT, PERTH); 13 km E of Irvin Creek, Petermann area, P.K. Latz 11682 (PCANB, DNA, NT, PERTH); 65 km W of Yulara, P.K. Latz 21077 (NT, PERTH); 16 km W of Armstrong Creek, J.R. Maconochie 1840 (NT, PERTH); 87 km W of Olgas on Docker River road, J.G. & M.H. Simmons 2430 (PERTH: phyllodes atypically narrow). W.A. (specimens sterile; identification to be confirmed): Mt Elevine, E of Warburton, A.S. George 3888 (PERTH); road to Giles from Docker River just after Rescue Creek, W of the WA-NT border, A. Kalotas 1531 (NT, PERTH);35 km NNE of Warburton, P.K. Latz 22096 (NT, PERTH)

Notes

Acacia sp. Mulga Blue Crown (D.E. Albrecht 9573) is seemingly most closely related to A. ayersiana which is most readily recognized by having shorter sepals (less than ½ the length of the petals), broader pod wings (1-2 mm wide) and normally less prominently recurved phyllodes. This probable new species may resemble morphotypes of Acacia aneura that possess recurved phyllodes, however, the latter are distinguished by phyllodes commonly narrower, lack a discrete resinous marginal nerve and often have winged pods. Furthermore A. aneura are normally multi-stemmed shrubs to about 5 m tall (rarely taller or single-stemmed, at least in N.T.) and are fire sensitive (P. Latz, pers. comm.). Acacia aneura is very rarely sympatric with Acacia sp. Mulga Blue Crown (D.E. Albrecht 9573) as it grows in heavier-textured red earth soils.

FOA Reference

Flora of Australia Project

Author

B.R.Maslin