Practical
Plants

Pittosporum tenuifolium

Tawhiwhi

a perennial woody evergreen member of the Pittosporum genus in the family Pittosporaceae.

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Taxonomy and growth

Life cycle
perennial
Foliage
evergreen
Woodiness
woody
Growth rate
moderate
Height
7 m
Spread
4 m
Fertility
Insects
Flower type
hermaphrodite
Pollinators
Insects

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

This plant contains saponins[4][5]. Saponins are found in many foods, such as some beans, and although they are fairly toxic to people they are poorly absorbed by the body and most pass straight through without any problem. They are also broken down if the food is thoroughly cooked for a long time. Saponins are much more toxic to some creatures, such as fish, and hunting tribes have traditionally put large quantities of them in streams, lakes etc in order to stupefy or kill the fish[K].

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

Gum - fragrant. It is obtained by bruising the bark or by incision[3][6].

Product or use
Gum

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

Very tolerant of trimming, plants can be grown as a formal or informal hedge in exposed maritime areas, though they do not stand extreme exposure[2][13][10]. When grown as a formal hedge it is best trimmed in spring, though this will mean that the plant will not produce many flowers[11]. A compromise is to only trim the hedge every other year[11].

Ecology and functions

Hedge

Environment

Range
New Zealand.
Habitat
Coastal to lower montane forests, North and South Islands, especially from North Cape and southwards[12].
Light
full sun
Shade tolerance
light shade
Water
moderate
Hardiness
Zone 8+
Soil textures
sandy, loamy
Soil pH
acid, neutral, alkaline
Drainage
well drained
Tolerances
high wind, maritime exposure
Wind
Yes
Maritime
Yes
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

Seed - sow when ripe in the autumn or in late winter in a warm greenhouse[14][10]. The seed usually germinates freely. Prick out the seedlings into individual pots when they are large enough to handle, move the plants to a cold frame as soon as they are established and plant out late in the following spring[14]. Consider giving them some protection from the cold during their first winter outdoors. Cuttings of half-ripe wood, 5 - 7cm with a heel, July/August in a frame. Poor to fair percentage[14]. Basal ripewood cuttings late autumn in a cold frame[10].

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Succeeds in most well-drained soils of reasonably good quality in full sun or light shade[1][10]. Succeeds in dry soils. Fairly tolerant of maritime exposure[13][7], but it can be killed by cold winds[8]. Hardy to about -10°c[8], it is tender outside the milder areas of Britain, but often self-sows when happy. Plants have reached a height of 9 metres in a sheltered position in eastern England[2]. A very ornamental plant[1], there are many named varieties[10]. Very amenable to pruning, plants can be cut right back into old wood if required[10]. The species in this genus are very likely to hybridize with other members of the genus[10]. When growing a species from seed it is important to ensure that the seed either comes from a known wild source, or from isolated specimens in cultivation. Plants are widely cultivated for their foliage which lasts a long time in water and is used in flower arranging[2][13]. The flowers are honey-scented[9]. Plants in this genus are notably resistant to honey fungus[10].

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

    ↩1↩2

  2. Bean. W. Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. Murray 1981-00-00

    ↩1↩2↩3

  3. Laing. and Blackwell. Plants of New Zealand. Whitcombe and Tombs Ltd 1907-00-00

    ↩

  4. Lassak. E. V. and McCarthy. T. Australian Medicinal Plants.

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  5. Ewart. A. J. Flora of Victoria.

    ↩

  6. Crowe. A. Native Edible Plants of New Zealand. Hodder and Stoughton 1990-00-00 ISBN 0-340-508302

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  7. Thomas. G. S. Ornamental Shrubs, Climbers and Bamboos. Murray 1992-00-00 ISBN 0-7195-5043-2

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  8. Phillips. R. & Rix. M. Shrubs. Pan Books 1989-00-00 ISBN 0-330-30258-2

    ↩1↩2

  9. Brickell. C. The RHS Gardener's Encyclopedia of Plants and Flowers Dorling Kindersley Publishers Ltd. 1990-00-00 ISBN 0-86318-386-7

    ↩

  10. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2↩3↩4↩5↩6↩7↩8

  11. Genders. R. Scented Flora of the World. Robert Hale. London. 1994-00-00 ISBN 0-7090-5440-8

    ↩1↩2

  12. Allan. H. H. Flora of New Zealand. Government Printer, Wellington. 1961-00-00

    ↩

  13. Rosewarne experimental horticultural station. Shelter Trees and Hedges. Ministry of Agriculture, Fisheries and Food 1984-00-00

    ↩1↩2↩3

  14. Sheat. W. G. Propagation of Trees, Shrubs and Conifers. MacMillan and Co 1948-00-00

    ↩1↩2↩3

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