Rata
Common name: Northern rata
Botanical name: Metrosideros robusta
The rata is unusual for a forest tree in that it generally starts life as an epiphytic seedling high in a host tree, as it requires plenty of light. It germinates from wind-borne seed that settles in a fork of the host tree or in a clump of epiphytes already perched on the host tree. It then sends down aerial roots to the ground and also side roots, which grow around the tree until they meet up with an aerial root again. Over hundreds of years the epiphyte roots completely enclose the trunk of the host tree and the rata eventually becomes a tall, often massive, forest tree with a hollow trunk (once the host tree dies and decays) and huge spreading branches. It can reach 25-30 metres in height with a trunk 2.5m in diameter and rarely as much as 7m in diameter!
Wide-spreading canopy
Sometimes a rata seedling grows on the forest floor rather than as an epiphyte. When it does this the tree takes a quite different form, with a trunk that is usually short, solid and crooked rather than a tall hollow trunk consisting of fused roots.
Rata ranges from the Three Kings Islands in the north, throughout the North Island and in the north-west part of the South Island down as far as Hokitika. It can be found from sea level up to 900m.
In spite of the rata’s huge size, possums can kill a mature tree in 2 years and in some parts of the country have contributed to a lot of rata die-back. Luckily that is not the case in Kaitoke Regional Park.
Leaves
The leaves are thick and leathery, up to 5cms long and 2cms across with rounded slightly indented tips, but as they are generally high above the ground they are difficult to use to help in identification without binoculars.
Leaves high in the canopy - sorry about the image quality
Flowers
CO Note: I will add some flower photos to the description once I get a chance to take some in the summer.
The flowers are similar to those of the related pohutukawa, but are smaller and usually a more intense red. They are borne in great profusion over the canopy of the tree in December and January making a rata in full bloom an impressive and unmistakeable sight.
Bark
The bark is rough and stringy and fissured in long narrow rectangles. Due to its texture it forms a good surface for many other epiphytes to grow, so on some trees it is hard to spot any rata bark.
Bark from the tree at GZ
The rata at GZ
There are a number of fine rata specimens in the Kaitoke Regional Park close to various tracks exhibiting varying degrees of encirclement of the host tree. The tree at GZ almost looks ‘normal’, unlike some in the park.
The rata at GZ even has a log-signing seat in front of it!
If you continue past GZ for another 400 metres there is a specimen on the right of the track that only has partially fused roots and is leaning at a precarious angle due to the weight of epiphytes that it is supporting. You are advised NOT to stand under this tree in a storm!
Aerial roots have not fully fused on this smaller leaning rata
The cache
The replacement cache is, like the original, a red M&M container and at time of placement contained a log sheet, a pencil, a pencil sharpener and three small trade items (a dinosaur, a rattle and a smiley fridge magnet). Please take your own writing implement to sign the log in case the pencil gets lost or too small to be useable. Online logs that do not have a matching signature in the paper log will be deleted. Please rehide it well so it cannot be seen by muggles who pass by or sit on the bench in front of the tree.