Page created 16 Jan 1997
Page updated 16 Jan 1997
Family: Myrtaceae (myrtle family) is a large family found throughout tropical and South America out to China and down through the Pacific. There is only one species of Myrtaceae in Europe, the classical myrtle(10). This family includes species such as pohutukawa, bottlebrush, Eucalypts, Feijoa, guava and strawberry.(1)(10) There are generally two types of fruit, either the fleshy, and usually edible, fruits such as Feijoa, guava and strawberry, or the hard woody capsules with very fine seeds like those that occur in the New Zealand species.(10) There are roughly 20 species of Metrosideros found from New Zealand to Malaya. The 11 New Zealand species are endemic (not found anywhere else).(2)
Scientific species name: Metrosideros robusta
Metrosideros means “iron-hearted” (from the Greek metra = middle and sideros = iron(3) ) referring to the hardness of the timber, robusta meaning stout, strong (2), solid or firm (8).
Maori name (s): Rata
Common name(s): Northern rata
Description: This is a tree up to 30 m tall or more. The trunk looks rather like that of a pohutukawa and is commonly up to 2 m in diameter. Kirk in his Forest Flora of New Zealand recorded one tree upwards of 7 m in diameter. The tree usually starts as a windblown seed lodged in decaying humus and leaf litter accumulated in the branch and trunk hollows of a large old tree. From there it sends roots down to the ground where it finds additional nutrition. The rata also sends “clasping” roots around the trunk of the supporting tree for extra security. Eventually the roots all join up to form one single trunk. This takes considerable time and by this time the host tree will probably have died of old age, leaving a hollow on the inside of the rata trunk.(2)
The northern rata was known as the “strangler rata” for a long time because people thought that the rata squeezed the host tree to death. However, research by Phillip Knightbridge has shown that seedlings only establish on large branches or in trunk hollows where humus has accumulated. A tree must be pretty old to have large branches and trunk hollows.(4)
It could well be that the rata hastens the end of the host tree somewhat, after all the rata canopy shades out part of the host tree canopy, and the rata roots compete with the host tree roots for the same food and water.
Northern rata can quite happily start as a seedling on the ground also, generally on a decaying log. In that case it will form trunks rather like those of the pohutukawa. (4)
The relatively thick leaves are flatter, thinner(11) smaller than the pohutukawa and not furry underneath. The pattern etc of the veins on the matt light green(5) underside of the leaves distinguishes the Northern rata from the Southern rata. Generally in the Southern rata only the main veins are seen, whereas in Northern rata copious net veins and margin veins are also visible. Both the upper and the lower surface of the Southern rata leaves are dotted with oil glands. The slight notch in the tip of the leaf of the Northern rata is also very characteristic.
The Northern rata flowers are bright red to dark-crimson and appear at the same time as pohutukawa flowers North of Auckland. Just like the pohutukawa these flowers produce lots of nectar at the base of the flower which is very popular with birds and insects. The flowers of the rata are slightly smaller than the pohutukawa, there are fewer flowers per umbel (an umbrella shaped group of flowers originating from a single stem), the yellow pollen is not as obvious as on pohutukawa flowers, and the cups that form the bases of the flowers are smooth and green (not covered with silvery fur like the pohutukawa).
The fruit is a woody capsule, up to about 6 mm across, that releases very fine hairlike seeds when ripe
Northern rata and pohutukawa cross-hybridise quite readily, there are many such examples on volcanic Rangitoto Island in the Hauraki Gulf. In that case the leaf can vary from looking totally Northern rata like to looking exactly like a pohutukawa leaf, or anything in between (for instance a small leaf with a notch (rata-like) with white fur on the lower surface (pohutukawa like)).
Distribution: Occurs in coastal to lower montane forest on the Three Kings Islands, throughout the North Island and in parts, mainly west of the divide, of the South Island to about latitude 42°30’.(2)
Uses: The timber is reddish-brown, immensely tough, strong and hard. The wood is often very distorted because of the way that the tree grows and hollow trees are common. Timber has been used for bridges, houses, furniture and makes excellent very hot burning firewood (11). The timber is also very popular with wood turners because of the beautiful but warped reddish grain, it can be very difficult to turn when it is dry though.
Juices from the Northern rata (and allied species) have been collected and drunk as a type of strengthening and astringent, but very wholesome, bush lemonade.(9)(12) The vine was cut and inverted and the juice collected, however a different author suggests that this was only done to another rata vine, M. scandens.(12)
Both Northern and Southern rata produce nectar that bees collect to make honey. It is very difficult to distinguish this honey as coming from Northern or Southern rata or from pohutukawa.(9) The nectar was used for sore throats.(12)
The flowers and bark are used in a similar way to pohutukawa. A lotion made from the bark was used for ringworm, aches, pains and wounds. A decoction made by boiling pieces of bark in water was said to be an old-time lotion for wounds. The bark was crushed, steeped and boiled and the liquid applied externally to bruises and taken internally for colds. The young leaves were chewed for toothache.(12)
Scientific species name: Metrosideros umbellata
Metrosideros means “iron-hearted” (from the Greek metra= middle and sideros = iron(3)) referring to the hardness of the timber, umbellata meaning “bearing umbels” an umbrella shaped group of flowers originating from a single stem).(2)
This species was earlier known as M. lucida (lucida = shiny).(6)
Maori name (s): Rata
Common name(s): Southern rata
Description: This is a shrub or tree up to 15 m tall or more that starts off on the ground.(2)(11) The trunk is up to 1 m or more in diameter and covered in pale papery bark that peels off in strips.(2)
Southern rata has long pointed leaves that are very shiny on the upper surface. The leaves are longer than those of the Northern rata, but more closely resemble Northern rata than pohutukawa. For a more detailed description of the leaves refer to Northern rata above. The young foliage is a pleasing brown or purple in colour and the tree puts on a spectacular display of crimson flowers.(6) An occasional yellow-flowered specimen can be found in Otira and Westland.(13) Young leaves and branchlets are silky to the touch.(7) The seed capsules are bigger than those of Northern rata.(14)
Distribution: Lowland to montane or occasionally subalpine forest and shrubland from 36° southwards. Southern rata is absent south of 38° in the North Island, except for a few scattered trees in the Tararua ranges, but is found throughout the South Island, especially west of the divide because it prefers the wetter climates(8) , Steward Island, Snares Island and the Auckland Islands. Southern rata is especially beautiful when it is flowering in the lower parts of the Otira.(2)
Uses: The timber is very similar to that of Northern rata and used in the same way.(11)
References:
(1) J.T. Salmon (1989) The native trees of New Zealand.
(2) Audrey Eagle (1978) Eagle’s 100 trees of New Zealand.
(3) Alison Evans & Stephen Barnett (1987) New Zealand in flower.
(4) Phillip Knightbridge (1993) The regeneration ecology of northern rata (Metrosideros robusta). (MSc thesis, University of Auckland).
(5) Rae West (1962) A guide to trees (Nature in New Zealand series).
(6) L. Cockayne (1923) The cultivation of New Zealand plants.
(7) A Poole & Nancy Adams (1994) Trees and shrubs of New Zealand.
(8) Muriel Fisher, E. Satchell & Janet Watkins (1985) Gardening with New Zealand plants, shrubs & trees.
(9) R.C. Cooper & R.C. Cambie (1991) New Zealand’s economic native plants.
(10) Colin Webb, Peter Johnson & Bill Sykes (1990) Flowering plants of New Zealand.
(11) Bruce Hamlin (1970) Nature in New Zealand. Native trees.
(12) S.G. Brooker, R.C. Cambie & R.C. Cooper (1987) New Zealand medicinal plants.
(13) J. T Salmon (1991) Native New Zealand flowering plants.
(14) Alison Evans & Stephen Barnett (1987) New Zealand in flower.
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