T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Plagianthus regius subsp. regius (Ribbonwood)

Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Malvales
Family: Malvaceae
Genus: Plagianthus
Species: P. regius
Subspecies: Plagianthus regius subsp. regius and Plagianthus regius subsp. chathamicus (Chatham Island ribbonwood)
Binomial name: Plagianthus regius
Synonyms: Plagianthus betulinus, Philippodendrum regium, Plagianthus betulinus var. betulinu, Plagianthus urticinus
Common name: Ribbonwood, Ribbon tree, Manatu, Lowland Ribbonwood,  Riverbank Ribbonwood,  MĀNATU, houi , houhi ongaonga, whauwhi, puruhi

Plagianthus regius subsp. regius is one of New Zealand’s few deciduous trees. Plagianthus regius is found over most of New Zealand, including Stewart Island and the Chatham Islands, but is absent from North Cape and Ninety Mile Beach in the far north. It grows in riparian habitats from sea level to 1500 ft, preferring moist soil. It has a distinct seedling, juvenile and adult forms.
The seedling form has an erect habit, and foliage similar to the adult form, but with truncate or cordate leaf bases. 
The juvenile form is a dense bush of slender, interlaced, branches. The leaves are ovate, >15mm × >10mm, and margins serrated. 
In its adult form, it is New Zealand's largest deciduous tree, reaching 15 m in height. The adult form, in its earlier stages, is a graceful, small to medium tree, reminiscent of the habit of a Silver Birch. When older it becomes broader and bulkier. A specimen growing in an open location in Christchurch has a spread of 15m and a trunk with a diameter of 1m.
The foliage consists of ovate to ovate-lanceolate, toothed, leaves > 7.5 cm long and > 5 cm wide, with a covering of stellate hairs on both surfaces. The leaves are strongly narrowed to the tip.
The yellowish-white flowers are small, 3-4 mm in diameter and hang in large, terminal panicles, in mid-spring. The male and females flowers are on different trees. Some male trees may have a few bisexual flowers. After the male flowers release their pollen they drop. The flowers petals are linear-oblong (narrower in male than in female flowers) and rounded at their tips. 
The fruit is a small, ovoid, creamy coloured, single-seeded, capsule, which on maturity splits down one side.
The tree’s bark will peel off in lace-like strips yielding a strong fibre that resembles flax and was used for tying.

A photo of an adult tree at California Park, Upper Hutt, New Zealand

Female flowers.

Mature fruits some have already dropped away, leaving sepals behind.

Branches of a juvenile tree

Adult leaves.

A juvenile leaf

The underside of a juvenile leaf.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0