Acacia helicophylla

Acacia helicophylla is a shrub belonging to the genus Acacia and the subgenus Juliflorae that is native to northern Australia.

Description
The shrub typically grows to a maximum height of 4 m. It has red-brown to blackish coloured minni ritchi style bark peels in long slender strips. The densely haired branchlets are mostly terete with angular upper branchlets slightly and have wide irregular bands of resinous tissue. Like most species of Acacia it has phyllodes rather than true leaves. The light green phyllodes have a narrowly oblong to oblanceolate shape that is undulate or spirally twisted. The hairy phyllodes have a length of 3.5 to 12.5 cm and a width of 6 to 30 mm and are narrower toward the base. They have six to eight longitudinal nerves with one prominent midnerve. It blooms between March and August producing golden flowers. The cylindrical flower-spikes occur singly or in pairs in the axils and have a length of 1.5 to 3.5 cm. Following flowering thinly coriaceous seed pods form that have a narrowly oblong shape and can be constricted between the seeds. The pods are 1.8 to 7 cm in length and 5 to 10 mm wide with fine hairs. The seeds within are arranged longitudinally. The dark brown swollen seeds have an elliptic shape and a length of 4.5 to 5.7 mm with an orbicular areole.

Taxonomy
The species was first formally described by the botanist Leslie Pedley in 1974 as part of the work Contributions from the Queensland Herbarium. It was reclassified as Racosperma helicophylla in 2003 by Pedley then transferred back to genus Acacia in 2006.

Distribution
It is endemic to the top end of the Northern Territory where it is found in a tropical climate in a small area in Nitmiluk National Park between Katherine Gorge and Gunlom Falls where it is usually situated on steep hillsides and on sandstone cliffs where it is found among rocks growing in skeletal sandy soils.