Common Name: Karo

General Information

Pittosporum crassifolium is an evergreen shrub or small tree with erect to ascending branches; it can grow from 1 - 10 metres tall[, ].
The plant is harvested from the wild for local use as a source of materials. The plant is often grown as an ornamental, where it is often used as a hedge - there are several named forms[]. It is a particularly useful street tree for heavily polluted inner city areas[].

Known Hazards

This plant contains saponins[].
Although poisonous, saponins also have a range of medicinal applications and many saponin-rich plants are used in herbalism (particularly as emetics, expectorants and febrifuges) or as sources of raw materials for the pharmaceutical industry. Saponins are also found in a number of common foods, such as many beans.
Saponins have a quite bitter flavour and are in general poorly absorbed by the human body, so most pass through without harm. They can be removed by carefully leaching in running water. Thorough cooking, and perhaps changing the cooking water once, will also normally remove most of them. However, it is not advisable to eat large quantities of raw foods that contain saponins.
Saponins are much more toxic to many cold-blooded 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 and make them easy to catch[].

Botanical References

, ,

Range

New Zealand - North and Kermadec Islands. Naturalized in Britain in the Scilly Isles[].

Habitat

Forest margins and by streams[], usually by the coast[].

Properties

Other Uses Rating
Habit	Evergreen Shrub
Height	5.00 m
Self-fertile	Yes
Cultivation Status	Ornamental, Wild

Cultivation Details

Pittosporum crassifolium is not very cold-hardy, when dormant it can tolerate short periods with temperatures falling to around -5°c[, ].
Succeeds in any well-drained soil[, ], including dry soils, preferably in a sunny position[] but also succeeding in light shade[]. Plants are very resistant to maritime exposure[, , , ]. Plants are very tolerant of atmospheric pollution[].
Very amenable to pruning, plants can be cut right back into old wood if required[].
The flowers are sweetly scented, they are borne in terminal clusters of either up to 10 males or up to 5 females[]. Plants only flower freely in mild areas of the country[].
Although flowers usually appear to be hermaphrodite, many species of Pittosporum are functionally dioecious, with individual specimens bearing mainly or totally flowers of one sex only. Even so, occasional functionally hermaphrodite flowers will appear and, in at least some species, these flowers can be self-compatible and produce fertile seed even in the absence of any other plants of that species[].
The species in this genus are also very likely to hybridize with other members of the genus[]. 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[].

Edible Uses

None known

Medicinal

None known

Agroforestry Uses:

Very tolerant of pruning and maritime exposure, this plant can be grown as a protective hedge by the coast in mild maritime areas[, , , ].
The plant has an extensive root system and can be used for binding sandy soils, dunes etc[].

Other Uses

A dark blue dye is obtained from the seeds[].

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!).

The wood is very tough. It is used for inlay[, ].

Propagation

Seed - sow when ripe in the autumn or in late winter in a warm greenhouse[, ]. 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[]. Consider giving them some protection from the cold during their first winter outdoors.
Cuttings of half-ripe wood, 5 - 7cm with a heel, mid summer in a frame. Poor to fair percentage[].
Basal ripewood cuttings late autumn in a cold frame[].