The New Zealand Plant Conservation Network

Species

Pittosporum obcordatum

Etymology

Pittosporum: pitch seed
obcordatum: reversed heart shape

Common Name(s)

Heart-leaved kohuhu

Current Conservation Status

2012 - Threatened - Nationally Vulnerable

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

Previous Conservation Status

2009 - Threatened - Nationally Vulnerable
2004 - Threatened - Nationally Endangered

Qualifiers

2012 - PD
2009 - CD, PD

Authority

Pittosporum obcordatum Raoul

Family

Pittosporaceae

Brief Description

Rare tall column-shaped shrub with interlaced wide-angled twigs bearing many scattered small rounded leaves and tiny yellowish flowers and small woody capsules. Leaves of a variety of shapes, 5-10mm wide, usually as long as wide. Juveniles leaves long, uneven, mottled. Fruit 6.5-10mm long, splitting into two.

Flora Category

Vascular - Native

NVS Species Code

PITOBC

Structural Class

Dicotyledonous Trees & Shrubs

Synonyms

Pittosporum obcordatum Raoul var. obcordatum, Pittosporum obcordatum var. kaitaiaensis Laing et Gourlay

Distribution

Endemic. New Zealand. Known from the North and South Islands. In the North Island it is known from Awanui south to the Wairarapa, with a primarily easterly distribution. In the South Island now known from several sites in the Catlins west to Lake Manapouri. About 40 plants were recently (2012) rediscovered by Melissa Hutchison on Banks Peninsula, the type locality of the species, after not being seen there for c. 170 years (Wilson, H. 2013. NZ Bot. Soc. Newsl. 112)

Habitat

A species of primarily eastern lowland alluvial forest, favouring sites prone to summer drought being otherwise waterlogged, and frost-prone during winter.

Features

Small, usually single-trunked columnar tree 5–8m tall. Branches numerous, interlacing, filamulate-divaricating. Branchlets grey to reddish-brown hairy, glabrate. Leaves alternate at seedling stage and on young branchlets, later confined to the tips of brachyblasts, numerous, tomentulose to glabrous, submembranous when young, coriaceous when adult, margins entire or crenate, flat or revolute, sparsely ciliolate; seedling lamina: 5.0–10.0 × 2.5–8.0mm, oblong, narrowly oblong, oblanceolate to elliptic, linear or spathulate, usually with apices deeply lobed, toothed and parted, sometimes entire, dark brown-green, dark green, ± mottled yellow-green; subadult lamina: 3.5–6.0 × 4.0–6.0mm, oblong, narrowly oblong to elliptic, obcordate-trilobate, dark green to yellow-green, sometimes mottled; adult lamina: 2.8–4.0 × 3.0–4.0mm, orbicular, obovate (with those near branchlet tips often rhomboid or entire); apex obcordate, to obtuse, base attenuate. Inflorescences on axillary or terminal, brachyblasts, 5–8mm long, 1–5-flowered umbellate, fascicles; pedicels c. 2mm, accrescent in fruit, pubescent, subtended by 1–5 leaves and numerous 1–2mm, caducous, sparsely ciliolate, pubescent bracts. Flowers night-fragrant, gynodioecious. Sepals 1.5–3.0 × 0.5–1.0mm, lanceolate-subulate, ovate-subulate, acute, ciliate; petals 4.0–6.5 × 0.7–1.5mm, linear-oblong, lanceolate, obtuse to subacute; connate as a short cylindrical tube with strongly reflexed tips, pink maroon or pale yellow, and then often with red-tinged margins, or striped red. Male flowers: stamens 4, filaments 2.5–4.5mm long, pink or yellow, anthers 0.5–1.0mm long, yellow or pinkish yellow; gynoecium rudimentary or functional. Female flowers: stamens 4 rudimentary (often reduced to staminodes); ovary 1.5–3.3 × 0.5–1.5mm, globose, finely pubescent to hairy; style 1.0–1.2mm long; stigma capitate, obscurely 2-lobed or truncate. Capsules 2-valved, 6.5–10.0 × 5.0–7.0mm, ovoid, subovoid to ellipsoid, apiculate, green to black, coriaceous, weakly rugose, sparsely hairy, glabrate; mucilage yellow. Seeds 2–6, irregular, globose, lustrous dark black.

Similar Taxa

Within the New Zealand species of Pittosporum this species is easily recognised. However, it has superficial similarity to a range of other small-leaved divaricating shrubs. P. obcordatum is most often confused with Myrsine divaricata A.Cunn. which can be best distinguished by the small, round, purple, fleshy fruits containing a single seed, and by the dark black blotch at the leaf base petiole junction.

Flowering

Late September to early December

Flower Colours

Red / Pink,Yellow

Fruiting

December to May but long persistent, such that fruit on well established plants may be found at anytime of the year.

Propagation Technique

Easily grown from fresh seed, Semi-hardwood cuttings though slow to strike and easily rooted. This species will tolerate a wide range of conditions but it does best in a moist, fertile soil in semi-shaded. It has an attractive columnar growth form, and the small flowers are produced in profusion and are pleasantly scented, particularly at night.

Threats

Primarily threatened by loss of habitat. Initially this was caused by the widespread clearance of the easterly, lowland alluvial forest habitats this species favours. However, decline has continued, even within many protected forest remnants due to subtle changes in forest microclimate and hydrology, bought about by habitat fragmentation, and also many populations are threatened by the spread of aggressive weeds, which suppress (or prevent) regeneration, and can smother adult trees. Some locations consist of single trees, which are then in effect reproductively extinct. However, like many Pittosporum, plants may be either female, male or sexually inconstant, so some isolated individuals can set seed.

Chromosome No.

2n = 24

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 19 Dec 2014