Metrosideros umbellata, the southern rātā, is a tree endemic to New Zealand. It grows up to 15 metres (49 ft) or more tall with a trunk up to 1 metre (3 ft 3 in) or more in diameter. It produces masses of red flowers in summer. Unlike its relative, northern rātā, this species rarely grows as an epiphyte.
Description
The flowers of southern rātā are scarlet, with stamens about 2 centimetres (0.79 in) long. White or yellow flowers are also known. Flowering usually occurs between December and February, but this depends on local conditions. Leaves are from 3 centimetres (1.2 in) to 6 centimetres (2.4 in) long, and are sharply pointed. The wood is hard, dense, and very strong. The bark is rough and flaky and provides an ideal stratum for the roots of epiphytic plants such as Astelia species and Freycinetia banksii (Kiekie). Southern rātā is a major source of honey on the West Coast of the South Island. The kākā, tūī, and bellbirds visit southern rātā to take advantage of the abundant nectar.
Southern rātā growing at its southern limits in the Auckland Islands at 50°S
Distribution
It prefers cooler regions with high rainfall and is particularly common along the west coast of the South Island where its nectar is the main source of a locally produced rātā honey. Southern rātā is the most widespread of the New Zealand tree rātā species. It is locally present in the North Island from latitude 36° southwards, is more common in western parts of the South Island but absent from much of the east, and is common on Stewart Island (47°S) and in the Auckland Islands, where it reaches its southern limit at just over 50°S.
Conservation
Although southern rātā is not regarded as threatened, it is rather uncommon in the North Island, and in certain areas it is threatened by possum browse. In the Tararua range, southern rātā populations appear to have been replaced by a population consisting of hybrids between northern and southern rātā.
Project Crimson is a charitable trust that promotes conservation of rātā as well as the related pōhutukawa.
Cultivation
Southern rātā is a beautiful specimen tree, but growth can be slow unless it is grown in ideal conditions with moist soil. It is easily grown from fresh seed. While it is possible to grow the tree from softwood or semi-hardwood cuttings, these often prove reluctant to strike roots. It is ideal for coastal environments because it has a good resistance to wind and salt.[2]
At least 16 cultivars of southern rātā have been released.[3] There are also known cultivars of hybrids between southern rātā and pōhutukawa, and between northern rātā and southern rātā.[4] Known cultivars include:
Sourced from the banks of the Avon River in Christchurch, between Madras and Manchester Streets. Source material provided by Mr Sparrow, a customer of the nursery. Despite the name, this cultivar is not a hybrid.
