Acacias of Australia

Print Fact Sheet

Acacia monticola J.M.Black x Acacia trachycarpa E.Pritz.




Occurs in the Pilbara region of north-western W.A. where it is known from a single collection along the railway access rd between Tom Price and Karratha.


Resinous shrub to 4 m high. Bark red ‘Minni Ritchi’. Branchlets hirtellous. Stipules persistent, triangular, c. 1 mm long, scarious, brown. Phyllodes linear-oblanceolate, narrowed to a fine, brown, subulate, innocuous point 1–1.5 mm long, upper margin clearly broader than lower margin, 4–8 cm long, 3–4 mm wide, not rigid, ±straight, sparsely hirtellous; longitudinal nerves numerous with central one most evident, minor nerves often longitudinally anastomosing. Inflorescences simple; peduncles 15–30 mm long, hirtellous; spikes 10–15 mm long. Flowers 5-merous; calyx dissected for about ½ its length into oblong lobes. Pods (immature) narrowly oblong, flat, 2–6 cm long, c. 8 mm wide, mostly straight, sometimes twisted in the longitudinal plane, obscurely reticulate, with dense, short, soft, straight, white hairs; marginal nerves thickened. Seeds (immature) oblique.


Grows in skeletal soil along a drainage line among low rocky hills.


W.A.: between Tom Price and Karratha along railway access track, E.Thoma 853 (PERTH).


The putative hybrid status of this entity is suggested by field observations and from a critical examination of herbarium material. It is intermediate between the two parents in phyllode width. Another putative hybrid between A. monticola and A. trachycarpa, not included in the above description, has been collected from near Nullagine but it seemingly no longer exists in that area. See B.R.Maslin et al., Wattles of the Pilbara CD-ROM (2010), for further discussion. Acacia trachycarpa also hybridizes with A. eriopoda and A. tumida var. pilbarensis in the Pilbara.

FOA Reference

Flora of Australia Project