The New Zealand Plant Conservation Network

Species

Pittosporum rangitahua

Etymology

Pittosporum: pitch seed
rangitahua: Rangitahua is believed by some to be the Maori name for Raoul Island. However, the connection of that name by iwi to that island is considered to be - at best - spurious.

Common Name(s)

Raoul Island kohuhu

Current Conservation Status

2015 - At Risk - Recovering

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Authority

Pittosporum rangitahua E.K.Cameron et Sykes

Family

Pittosporaceae

Brief Description

Small densely branched tree with erect branches. Young broanchelst covered in white hairs. Leaves crowded toward branchlet apices. Leaves oblanceolate, with densely white-hairy undersides and mostly hairless, gloosy upper surfaces. Flowers red-purple borne in terminal 3-14-flowered umbels. Fruits capsular, globose 2-3-valved; seeds 20-30 per fruit, blossy black, embedded in sticky yellow to yellow-orange mucilage.

Flora Category

Vascular - Native

Structural Class

Dicotyledonous Trees & Shrubs

Synonyms

None - first described in 2015

Distribution

Endemic. Kermadec Islands group, Raoul Island only

Features

Densely branched small tree 3–8 m tall. Primary branches erect, with secondary and tertiary branches erect to ascending. Branchlets are at first densely white-tomentose, becoming grey-brown and sparsely tomentose with aging; bark smooth, grey-brown and glabrous. Leaf scars consistently have three vascular bundles. Leaves are crowded towards the ends of bare branches

Similar Taxa

Differs from Pittosporum crassifolium and P. fairchildii by the usually narrower leaf shape, wider angle of the secondary leaf veins, thinner and more erect branches, longer and narrower sepals, generally longer and wider petals, 2-valved and smaller capsules, and sharp-angled seeds. Leaves entire, alternate, coriaceous, oblanceolate, 40–97 × 10–27 mm, 3–6x longer than broad; weakly revolute with the midrib slightly sunken; apex subacute to rounded; base cuneate; petioles 5–10 mm long; adaxial leaf surface initially covered in dense white tomentum, soon deciduous and revealing a bright green leaf surface. Adaxial surface with dense white felted hairs which thin out as the leaf ages. Secondary leaves are alternate, entire, leaf lamina with fringe of marginal hairs, and few-many hairs along the midrib (especially on the abaxial side), otherwise glabrous; petiole sparsely hairy. Inflorescences terminal umbels with (3–)6–14 flowers per umbel. Subtending bracts are few, caducous, linear, 5–11 mm long, covered in off-white tomentum. Pedicels 10–25 mm long, covered in off-white tomentum. Flowers gynodioecious, sweetly scented. Sepals 5, unequal, 6–11 × 1.0–2.5 mm, narrow-triangular, acute-tipped; except for lower adaxial surface, covered in off-white tomentum, do not reflex (deciduous by fruiting stage). Petals red-purple (occasionally paler), free, 12–17(–19) × 4–6 mm, ± oblong-obovoid, upper third becoming reflexed, ± glabrous. Stamens 5, antisepalous, dorsifixed. Ovary superior, pilose, gynoecium of two fused carpels. Style unbranched. Capsule 2 (-3)-valved, globose, 12–18 mm diameter; valves whitish tomentose outside, pale brown and rugose inside, becoming woody at dehiscence; peduncles erect to spreading. Seeds are 20–30/capsule, viscid, lustrous black, irregular, 4.0–5.5 mm long, and many flat faces meeting along ± sharp edges

Fruiting

Present throughout year

Propagation Technique

Easily grown from fresh seed. However plants are often short-lived and very susceptible to phytophthora

Threats

Known only from Raoul Island where this species occurs in scattered and often small populations. Following goat and rat eradication from the islands (declared free of major mammalian pests in 2006) this species has started to expand it range. Currently there is an estimated adult population of 1000 individuals, which is actively increasing. For this reason the species, listed as as Pittosporum aff. crassifolium (AK 253259; Raoul Island) had been assessed as 'At Risk / Recovering' by de Lange et al. (2012). Cameron & Sykes (2015) have upheld this assessment. However, should Phytophthora reach the Kermadecs it is likely that this species would then be seriously at risk of extinction.

Chromosome No.

2n = 24

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 19 Oct 2015