Plant profiles > Pomaderris
Family : Rhamnaceae
The members of this genus bear some of the most conspicuous flowering displays in the New Zealand flora. These range from the early spring appearance of kumarahou's large, albeit short-lived, yellow flowerheads, to the abundantly-borne frothy cream inflorescences of species like tauhinu (Pomaderris amoena) and P. rugosa. They are plants of open ground, often growing in impoverished soil - such as is found in scrub conditions or cliff habitats. It is, therefore, easy to understand one of their requirements or successful cultivation - Pomaderris spp. do not respond well to the application of fertiliser.
Pomaderris is an exclusively Australasian genus of around forty species, most of which are confined to Australia. Of the seven New Zealand species, four are endemic to our country. Pomaderris is part of the widespread buckthorn family (Rhamnaceae). It is interesting to note that the only other New Zealand plant from this family is the matagouri (Discaria toumatou), a shrub of drier areas of New Zealand (especially colder regions). This thorny character bears little resemblance to the species of Pomaderris, but shares a preference for open habitats like grassland and scrub.
Many of these types of open ecologies fit into the description of seral communities - that is, communities of plants that are 'intermediate' in nature, occupying a place between bare ground and the final vegetation types (like forest) that will cover a given area. Although essentially transitional, seral ecologies are not always short-lived, as nature works on cycles that don't necessarily relate to our own lifecycles. Two examples are the kinds of tussockland or shrubland that are found in the dry east of the South Island. Neither are 'climax' communities, but it would take hundreds of years (or longer) for many of these areas to return to their climax vegetation type.
Even without human disturbance (which opens up landscapes in unnatural ways), seral ecologies are part of the matrix of habitats that form natural landscapes. They occur in permanently open habitats (like rocky ground and cliffs), and in places where storm events have opened up the landscape. When one considers the place of Pomaderris in these habitats, one can understand their potential role in gardens better.
Pomaderris amoena
Tauhinu
This attractive little shrub adorns many of our roadside banks, where its slightly cascading mounds of fine foliage are covered in sprays of creamy flowers as spring turns to summer. They are well adapted to the difficult conditions of these places, including the regular trimming applied by tractors to keep vegetation back from the road. The plants in the population photographed on the right were cut back to close to ground level soon after this image was taken, and are already regrowing (thankfully, contractors at that site use this method instead of spraying, which would kill the plants).
P. amoena is also found in more natural associations, such as dry shrubland of the kind found on the east coast of the North Island. In addition to the cream flowers, the leaves are often a highly attractive bright green colour. Due to its tolerance of harsh conditions, it is a useful species for plantings in difficult positions, such as steep clay banks or infertile ground.
As stated above in the main description of Pomaderris, this plant does not respond well to fertiliser (although it shows a greater tolerance to it than other species like P. kumeraho and P. rugosa). This preference for infertile conditions can, in fact, be turned to good advantage in the weed-prone environments of northern New Zealand. By eliminating the need for fertiliser in a given area, one decreases its suitability for a number of weed species (thereby reducing the range of weeds that may occupy it).
Tauhinu (its common name in Māori) is a somewhat confusing title, as it is also applied to members of the genus, Ozothamnus, that are commonly found in coastal and shrubland habitats. This has evolved out of the similarities between the species concerned (despite their botanical distinctness). Another example is the use of the name mingimingi for a considerable number of filiramulate shrubs that bear a likeness to each other.
