Acacias of Australia

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Acacia sp. Marble Bar (J.G. and M.H.Simmons 3499)




Confined to Pilbara region of north-western W.A. where it is known from a single collection near Marble Bar.


Shrub. Branchlets scurfy, moderately to densely sericeous at extremities, indumentum sparser with age. New shoots resinous. Phyllodes narrowly oblong to oblong-elliptic, straight but some shallowly incurved, (4.5–) 5–7 cm long, (6–) 8–10 mm wide, obtuse-mucronate with a short, conical, hard point, moderately to densely sericeous, dull green; longitudinal nerves numerous with central one the most pronounced, often a sub-prominent nerve extends from the pulvinus to intersect the upper margin in lower ¼ of phyllode, minor nerves close together with some longitudinally anastomosing, the upper margin slightly broader than lower margin; gland at distal end of pulvinus. Inflorescences simple, 1 or 2 per axil; peduncles 3–5 mm long, ±sparsely sub-appressed puberulous; spikes 25–30 mm long, golden, the flowers sub-densely arranged; receptacle with sparse, patent to ±appressed hairs. Flowers 5 merous; calyx 1/3 length of corolla, dissected for about ½ its length; petals glabrous, obviously 1-nerved. Pods and seeds not seen.


It probably grew in unconsolidated sand along a seasonal watercourse among low rocky hills but the original population has seemingly has been killed by fire, fide B.R.Maslin et al., Wattles of the Pilbara CD-ROM (2010).


W.A.: 14 km on Corunna Rd out of Marble Bar, J.G. & M.H.Simmons 3499 (PERTH).


The taxonomic status of this entity, which was recognized in B.R.Maslin et al., loc. cit., is uncertain but it may be a hybrid involving A. trachycarpa which grows in the area where the original plant was found. The slightly widened upper margin of the phyllodes suggests this relationship. If it is a hybrid involving A. trachycarpa then the second parent is currently unknown. The presence of a moderately dense indumentum of appressed hairs on the branchlets and phyllodes is unusual, as is the sub-prominent nerve that extends from the pulvinus to the upper margin.

FOA Reference

Flora of Australia Project