Acacia alaticaulis

General Plant Info

Acacia alaticaulis is named after it's distinctive winged branchlets, derived from Latin alatus (meaning ‘winged’) and caulis (meaning ‘stem’). It is a spindly or straggly shrub to small tree to 4 m high, with bipinnate leaves, flowers from December to May and fruits in November. Grows in sandy and sandy clay soils, on ridges and hillslopes, on sandstone or at the junction of shale and sandstone, in eucalypt woodland or open forest with shrub understorey.

The known populations of Acacia alaticaulis are protected in the Yengo National Park, and although not listed as 'threatened' under state or federal legislation, it has been indicated as 'rare', as a ROTAP taxon with the code 2RC-t, has a geographic range of less than 100 km, and the total known population occurs in a proclaimed reserved.

Closely related to Acacia terminalis and Acacia kulnurensis

Acacia alaticaulis differs from Acacia terminalis by the markedly winged branchlets, petioles and rachises (less pronounced winged ridges may occur in Acacia terminalis), shorter petioles to 5 mm long, markedly recurved pinnules (pinnules may be slightly recurved in Acacia terminalis) and usually smaller petiolar gland 1–2 mm long (1.2–12 mm long in Acacia terminalis).

Acacia alaticaulis can be distinguished from Acacia kulnurensis by the winged branchlets, petioles and rachises, and almost glabrous branchlets and foliage, as well as often having shorter bracts at the base of the peduncles and slightly narrower legumes.

Geographic distribution

Occurs in the vicinity of Howes Mountain (6–7 km NE of Howes Valley, E of Putty Road) and along Old Convict Road to Mount Murwin (c. 10 km ESE of Howes Valley), Hunter Range, Yengo National Park. Also recorded further north around Mount Isobel (Maryott-Brown and Wilks 1993). Locally occasional to scattered.

Identification

Spindly or straggly shrub to small tree to 4 m high; branches often pendulous. Branchlets glabrous or very sparsely puberulous, with convoluted, winged ridges to 3 mm high. Leaves dark to mid-green above, paler below; petiole to 5 mm long, winged, glabrous or almost so, with a gland 1–2 mm long; rachis 1.4–8.5 cm long or absent, winged, glabrous or sparsely puberulous, often with a small gland at base of terminal and rarely other pair(s) of pinnae, interjugary glands absent;

pinnae 1–10 pairs, 1.2–6 cm long; pinnules 7–17 pairs, well-spaced, oblong to narrowly oblong, narrowly ovate to lanceolate or narrowly obovate, 2.5–11 mm long, 0.9–3.6 mm wide, recurved, mostly glabrous, apex acuminate or acute.

Inflorescences in axillary or terminal racemes or panicles; axes to 33.5 cm long, winged. Heads 6–16-flowered, cream-coloured to pale yellow.

Pods straight-sided or sometimes irregularly constricted between seeds, usually curved, 6–12 cm long, 11–13 mm wide, coriaceous, reddish brown or blackish brown, with minor transverse veins, sometimes rough over seeds, glabrous; margins prominent, paler.

Links

http://openjournals.library.usyd.edu.au/index.php/TEL/article/view/7055/7762

http://www.worldwidewattle.com/speciesgallery/alaticaulis.php

http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=wattle&lvl=sp&name=Acacia~alaticaulis