Acacia subporosa, also commonly known as river wattle,[1] bower wattle, narrow-leaf bower wattle and sticky bower wattle,[2] is a tree or shrub of the genus Acacia and the subgenus Plurinerves that is endemic to an area of south eastern Australia. It is considered to be rare in Victoria[3]
The tree or shrub typically grow to a height of and has an erect or spreading[1] or rounded habit and a low canopy with a width of around [4] with weeping branches that have smooth grey or born coloured bark smooth. It has sticky and glabrous branchlets that have green to brown alternating ridges.[1] Like most species of Acacia it has phyllodes rather than true leaves. The thin and glabrous phyllodes have a very narrowly elliptic shape than can be slightly to moderately incurved with a length of and a width of and have two to five main nerves per face and other less pronounced longitudinal nerves in between.[2] It blooms between July and October and occasionally into the summertime producing pale yellow flowers.[1] The simple inflorescences occur singly or in groups of up to three in the axils and have spherical flower-heads with a diameter of containing 20 to 25 flowers. Following flowering firmly chartaceous and glabrous seed pods are formed that are linear with a length of up to and contain glossy dark brown seeds with an oblong shape, a length of about and a small terminal aril.[2]
The species was first formally described by the botanist Ferdinand von Mueller in 1863 as a part of the work Fragmenta Phytographiae Australiae , the initial spelling was Acacia supporosa.[1] It was reclassified as Racosperma subporosum by Leslie Pedley in 2003 then transferred back to genus Acacia in 2006.[5] The type specimen was collected by von Mueller from Twofold bay in New South Wales.[2] The specific epithet is derived from the small oil glands on the phyllodes. The species is closely related to Acacia cognata[1] and both belong to the Acacia verniciflua complex.[2]
It is native to coastal areas of south eastern New South Wales and north western Victoria.[1] The range of the plant extends from around Bega in the north to around Howe Hill on the north eastern tip of the Victoria-New South Wales border in the south[2] in the far east Gippsland area.[3] It is commonly situated along creeks and streams in gullies or on low hillsides found near the margins of rainforest communities growing in moist sandy or shale-based soils and conglomerates.[2] It is often associated with Acacia longifolia.[6]
The tree is used as street trees or as a screening plant, it can grow at a rate of about per annum and live for almost 50 years. The plant is susceptible to root rot and shothole borer.[4]