Carpodetus serratus is an evergreen tree with small ovate or round, mottled leaves with a toothy margin, and young twigs grow zig-zag, and fragrant white flowers in 5 cm panicles and later black chewy berries.

Its most common name is putaputāwētā which means many wētā emerge - referring to the nocturnal Orthoptera that live in holes in the trunk of this tree made by Pūriri moth caterpillars.

It develops a slender trunk of up to 30 cm in diameter, which is covered by rough and corky bark, has a mottled grey-white colouring and is often knobbly due to boring by insects.

The inflorescences are panicles of 5 cm in diameter and consist of up to fifteen or more flowers at the leaf axil or at the end of branches.

The anthers are connected to the filaments at their base, open in lengthwise slits towards the inside, through which the yellow pollen is shed in tetrads.

The fruit is a somewhat fleshy round berry of 4–6 mm that turns black when it ripens, the lower half is cupped by the remains of calyx.

[12] The fact that freshly cut wood contains so much sap that it is difficult to burn gave rise to the name bucket-of-water-tree.

[5] The workers of Prolasius advenus (small brown bush ant) feed on the sap trickling from the wounds in the tree caused by the caterpillars.

It remains a compact, rounded shrub for several years before finally developing its adult tree-like form.