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

Plagianthus regius (Ribbonwood)

Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Malvales
Family: Malvaceae
Genus: Plagianthus
Species: P. regius subsp. regius
Binomial name: Plagianthus regius subsp. regius
Synonyms: Plagianthus betulinus, Philippodendrum regium, Plagianthus betulinus var. betulinu, Plagianthus urticinus
Common name: Ribbonwood, Ribbon tree, Manatu, Lowland Ribbonwood,  Riverbank Ribbonwood.

The genus name is a reference to the petals of a Plagianthus flower which are all the same size. The genus Plagianthus, as currently recognised, is endemic to New Zealand and the Chatham Islands.
Plagianthus regius subsp. regius a deciduous (looses all of its leaves for part of the year) New Zealand tree. 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 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, 5-15mm × 3-10mm, and 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 in habit of a Silver Birch. (Hence, the synonym Plagianthus betulinus). 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, from 1"-2½" long, and ¼"-2" wide, with a covering of stellate hairs on both surfaces. 
The yellowish-white flowers are small, but occur in large, terminal panicles, in late spring. The petals are linear-oblong (narrower in male than in female flowers) and rounded at their tips. The fruit is a small, ovoid, single-seeded, capsule, which on maturity splits down one side.
The inner bark yields a strong fiber that resembles flax and is called New Zealand cotton.

Adult tree at California Park, Upper Hutt, New Zealand

A branches of a juvenile tree

Adult leaves.

A juvenile leaf

The underside of a juvenile leaf.