"Acacia pycnantha" generally grows as a small tree to between in height, though trees of up to high have been reported in Morocco. The bark is generally dark brown to grey—smooth in younger plants though it can be furrowed and rough in older plants. Branchlets may be bare and smooth or covered with a white bloom. The mature trees do not have true leaves but have phyllodes—flat and widened leaf stems—that hang down from the branches. Shiny and dark green, these are between long, wide and falcate (sickle-shaped) to in shape. New growth has a bronze colouration. Field observations at Hale Conservation Park show the bulk of new growth to take place over spring and summer from October to January.