Practical
Plants

Pittosporum crassifolium

Karo

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
Height
5 m
Spread
3 m
Fertility
self fertile
Flower type
monoecious

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[2]. 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].

Material uses

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

A dark blue dye is obtained from the seeds[3]. The plant is a potential source of saponins. Saponins can be used to as a soap and, because of their bitter taste, they also have potential as a bird deterrent by spraying them over the plants. The bitterness can be easily removed by washing (or by the next rainfall!). Very tolerant of pruning and maritime exposure, this plant can be grown as a protective hedge by the coast in mild maritime areas[1][8][11][13]. The plant has an extensive root system and can be used for binding sandy soils, dunes etc[2]. Wood - very tough. Used for inlay[10][12].

Product or use
Dye
Product or use
Soap
Product or use
Wood

Ecology and functions

Hedge

Earth stabiliser

Environment

Range
New Zealand. Naturalized in Britain in the Scilly Isles[4].
Habitat
Forest margins and by streams on North and Kermadec Islands[9].
Light
full sun
Shade tolerance
light shade
Water
moderate
Hardiness
Zone 9+
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][6]. 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[6].

Cultivation

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

Succeeds in any well-drained soil[5][6], including dry soils, preferably in a sunny position[5] but also succeeding in light shade[6]. Plants are very resistant to maritime exposure[1][8][13][6]. This species is not very cold-hardy in Britain, succeeding outdoors only in the milder areas of the country[1]. Plants grow very well on the Scilly Isles but have not been proved on the mainland[8].Other reports say that it grows well in south-western England[1][11]. Very amenable to pruning, plants can be cut right back into old wood if required[6]. The flowers are sweetly scented, they are borne in terminal clusters of either up to 10 males or up to 5 females[7]. Plants only flower freely in mild areas of the country[7]. The species in this genus are very likely to hybridize with other members of the genus[6]. 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 in this genus are notably resistant to honey fungus[6].

References

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

    ↩1↩2↩3↩4

  2. Brooker. S. G., Cambie. R. C. and Cooper. R. C. Economic Native Plants of New Zealand. Oxford University Press 1991-00-00 ISBN 0-19-558229-2

    ↩1↩2

  3. Buchanan. R. A Weavers Garden.

    ↩

  4. Clapham, Tootin and Warburg. Flora of the British Isles. Cambridge University Press 1962-00-00

    ↩

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

    ↩1↩2

  6. 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

  7. Grey-Wilson. C. & Matthews. V. Gardening on Walls Collins 1983-00-00 ISBN 0-00-219220-0

    ↩1↩2

  8. Shepherd. F.W. Hedges and Screens. Royal Horticultural Society. 1974-00-00 ISBN 0900629649

    ↩1↩2↩3

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

    ↩

  10. Uphof. J. C. Th. Dictionary of Economic Plants. Weinheim 1959-00-00

    ↩

  11. Arnold-Forster. Shrubs for the Milder Counties.

    ↩1↩2

  12. Usher. G. A Dictionary of Plants Used by Man. Constable 1974-00-00 ISBN 0094579202

    ↩

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

    ↩1↩2

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

    ↩1↩2↩3

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