The Pittosporum Family
What are they?
This is a family of woody plants that is largely confined to the southern hemisphere and the tropical regions of the world with just a handful of species introduced into the UK as garden ornamentals. Within the family, the genus Pittosporum is popular as a group of evergreen shrubs that are weather-tolerant of coastal conditions and are commonly planted on the Isles of Scilly for hedging and screening. A single species has been cultivated to produce a range of named varieties.
Where are they found?
Hedges of Pittosporum are a common sight around the islands and, in more recent years, self-sown plants have began to appear more widely.
Identification
Pittosporums are evergreen shrubs or small trees. Their flowers are unlike those of any of our native plants and these, together with the leaves, should help to identify the species.
Karo Pittosporum crassifolium
Introduced from New Zealand and widely planted as a windbreak, especially around bulb fields. Recorded as self-seeding on all of the medium to large islands. Flowers April to June. An evergreen shrub or small tree to 10m tall. Leaves 5-7cm long and 2-2.5cm wide, leathery, paler below, tapered (cuneate) at the base. Flowers unisexual, maroon to dark purple, on female plants followed by green fruits.
Note: the rather similar Pittosporum ralphii has been recorded from Tresco. It resembles Karo but has bisexual flowers and leaves that are rounded at the base.
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Kohuhu Pittosporum tenuifolium
Introduced from New Zealand as a garden ornamental and recorded from St Mary's and Tresco. Flowers April to June. Evergreen shrubs, capable of growing to over 10m in height when free-growing but often cut as hedging. Leaf-bearing branches are thin and wiry and blackish on colour. Leaves are shiny and usually have strongly waved edges. Flowers are five-petalled and deep reddish-purple or maroon in colour and are followed by rounded seed capsules.
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Kohuhu cultivars Pittosporum tenuifolium
In cultivation, Kohuhu has produced a wide range of cultivated varieties which mostly differ in the colour of their leaves. Some are shown here as they may not immediately be identifiable using the details given under the species above. In particular, the cultivar 'Tom Thumb' forms a small, rounded bush and is sometimes used in amenity plantings in more formal situations.
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Japanese Cheesewood Pittosporum tobira
Native to South Korea and Japan and introduced as a garden ornamental. Recorded from the Garrison, St Mary's. Flowers May to September. An evergreen shrub, capable of growing to over 5m in height when free-growing but often cut as hedging. Leaves are glossy and leathery, up to 10cm long and often become reflexed along their length as they age. Flowers are five-petalled, white, fading to yellowish-cream and very heavily scented.
This plant should be familiar to anyone visiting the Mediterranean region as it is enormously popular as a hedging plant in hotel gardens there.
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