Pomaderris is a genus of approximately 80 species of flowering shrubs and small trees in the family Rhamnaceae, order Rosales. The genus is predominantly native to Australia, occurring in all states and the Australian Capital Territory, with around five species extending to both the North and South Islands of New Zealand.
Plants in the genus are typically multi-stemmed shrubs, occasionally reaching small tree size. A defining characteristic is the dense covering of woolly, star-shaped (stellate) and simple hairs on young stems, the undersides of leaves, and flower parts, giving the plants a soft, grey-green appearance. The leaves are simple and arranged alternately along the branches, bearing small brown stipules at the base of the leaf stalk that are usually shed as the leaf matures.
The flowers are small, usually yellow, and arranged in small cymes that are in turn grouped into racemes or panicles, producing frothy, cloud-like displays when in bloom. One of the most notable features of the genus is that the petals are frequently absent or fall away as the flower opens — the genus name Pomaderris alludes to another distinctive feature: it means "a covering of leather or skin" in reference to the capsule fruit, which splits at maturity into three valves.
The genus was first formally described in 1805 by the French botanist Jacques Labillardière in his work Novae Hollandiae Plantarum Specimen, making it one of the earlier Australian genera to receive formal scientific treatment. Well-known members include Pomaderris aspera (hazel pomaderris) of southeastern Australia and Pomaderris kumerahou, a coastal shrub of New Zealand sometimes called gumdigger's soap.
Etymology
The genus name Pomaderris derives from Greek roots meaning "a covering of leather or skin," a reference to the leathery valves of the capsule fruit that split open at maturity. The name was applied by Jacques Labillardière when he formally described the genus in 1805.
Distribution
Pomaderris species are found across all Australian states and the Australian Capital Territory, but are absent from the Northern Territory. Approximately 65 species are endemic to Australia, while five species occur in New Zealand, where the genus is present on both the North and South Islands. There is some degree of overlap between Australian and New Zealand species.
Ecology
Pomaderris species serve as larval food plants for certain Lepidoptera, including the moth Aenetus ligniveren. The dense stellate hairs covering leaves and stems are thought to provide some defence against herbivory and desiccation in the often dry or seasonally arid Australian habitats where many species grow.
Taxonomy Notes
The genus was first formally described in 1805 by Jacques Labillardière in Novae Hollandiae Plantarum Specimen. Pomaderris belongs to the family Rhamnaceae, order Rosales. The genus contains approximately 80 accepted species, the majority endemic to Australia, with a smaller contingent native to New Zealand.
