Pittosporum rangitahua
Common name
Raoul Island kōhūhū
Synonyms
None - first described in 2015
Family
Pittosporaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Trees & Shrubs - Dicotyledons
Chromosome number
2n = 24
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – an interim threat classification status has not been assessed by the NZTCS panel.
- Conservation status of New Zealand indigenous vascular plants, 2017 . 2018. Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | At Risk – Recovering | Qualifiers: CD, IE, OL
Previous conservation status
2015 | At Risk – Recovering
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.
Distribution
Endemic. Kermadec Islands group, Raoul Island only
Detailed description
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.
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.
Attribution
Fact sheet prepared by P.J. de Lange (19 October 2015). Description modified from Cameron & Sykes (2015).
References and further reading
Cameron, E.K.; Sykes, W.R. 2015: Pittosporum rangitahua sp.nov. from Raoul Island, Kermadec islands, northern New Zealand. Auckland Museum Bulletin 20: 253-262.
de Lange, P.J.; Rolfe, J.R.; Champion, P.D.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Norton, D.A.; Hitchmough, R.A. 2013: Conservation status of New Zealand vascular plants, 2012. New Zealand threat classification series 3. Department of Conservation, Wellington. 70 pp.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Pittosporum rangitahua Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/pittosporum-rangitahua/ (Date website was queried)