Sweet Pittosporum
Pittosporum undulatum
NEMBA category
English: Sweet Pittosporum, Australian Cheesewood, Mock Orange, Victorian Box, Native Daphne
Afrikaans: Kleefsaad, Australiese Kaasbos
Historical scientific names: Pittosporum revolutum var. undulatum, Pittosporum undulatum var. angustifolium, Pittosporum undulatum var. reticulatum
Pittosporum undulatum, commonly known as Sweet Pittosporum or Australian Cheesewood, is a fast-growing, evergreen shrub or small tree. It is easily identified by its glossy, wavy-edged leaves, clusters of intensely fragrant, creamy-white flowers, and woody capsules containing sticky orange seeds.
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Origin:
South-eastern Australia (Victoria, New South Wales, and Queensland).
Distinguishing features:
Glossy, dark green leaves with distinctly wavy (undulate) margins.
Very fragrant, creamy-white, tubular flowers in clusters.
Woody, orange, two-valved capsules containing sticky, reddish-orange seeds.
Dense, conical to rounded crown.
Evergreen foliage.
Overall appearance:
Pittosporum undulatum grows as a dense, upright, evergreen shrub or small tree with a conical to rounded crown. Its dark green, glossy foliage provides year-round appeal, and it is particularly striking when in bloom due to its profusion of fragrant flowers.
Height:
Typically grows 5 to 10 metres tall, but can sometimes reach up to 15 metres or more.
Width:
It can spread to a width of 3 to 6 metres, forming a dense canopy.
Leaves:
The leaves are alternately arranged, simple, and elongated (lance-shaped to oblanceolate), 6-15 cm long and 2-4 cm wide. They are glossy, dark green on the upper surface, paler underneath, and have distinctively wavy (undulate) margins. The leaves are smooth and hairless.
Flowers:
The flowers are small, star-shaped with five creamy-white petals that are typically twisted and reflexed. They are tubular at the base, about 1-2 cm long, and produced in dense, branched clusters (cymes) at the ends of branches. They are intensely fragrant, especially at night, with a sweet, orange-blossom-like scent. Pittosporum undulatum flowers are hermaphroditic, containing both male and female reproductive parts, so it is not dioecious.
Flowering season:
In South Africa, it primarily flowers in late winter to spring (around July to October), with fruits developing and maturing through summer and autumn. Its early flowering makes it particularly noticeable.
Fruits:
The fruits are spherical to egg-shaped, woody capsules, about 1-1.5 cm in diameter. They are initially green and turn orange-brown or yellowish-brown as they mature, eventually splitting open into two valves to reveal the seeds.
Seeds:
Each capsule contains 20-30 bright reddish-orange seeds, which are coated in a sticky, resinous pulp. The stickiness of the seeds aids in their dispersal by birds and other animals, as they can stick to feathers, fur, or even shoes.
Bark:
The bark on young stems is smooth and green. As the tree matures, the bark on the trunk becomes greyish-brown and can be somewhat rough or fissured.
Thorns:
This plant does not have thorns.
Wood:
The wood is relatively soft and pale. It is not considered commercially valuable timber.
Roots:
It has a fibrous, somewhat shallow, but extensive root system. Its roots can be quite competitive and can sometimes lift paving or interfere with pipes.
Soil type:
It is adaptable to a wide range of soil types, including sandy, loamy, and clay soils, provided they are well-draining. It tolerates poor soil conditions but thrives in moist, fertile soils.
Aspect:
Prefers full sun to partial shade. It is moderately tolerant of frost once established but thrives in warm, moist climates and coastal conditions.
Edibility:
The plant is generally not considered edible. While the leaves might have some traditional medicinal uses in its native range, they are not consumed as food. The sticky seeds are also not for consumption.
Toxicity:
Generally considered to have low toxicity, but ingestion of leaves or berries could cause mild gastrointestinal upset in sensitive individuals or pets. The main concern is its invasive potential.
Uses:
Primarily cultivated as an ornamental plant in gardens, parks, and for hedging due to its attractive evergreen foliage, fragrant flowers, and dense growth habit. Its ability to tolerate coastal conditions also made it popular.
Ecology:
As a highly aggressive alien invasive species in South Africa, Pittosporum undulatum poses significant ecological threats by:
Forming dense monocultures: It rapidly invades natural areas, particularly forest margins, woodlands, fynbos, and grasslands, forming dense, impenetrable thickets that completely shade out and replace indigenous vegetation.
Altering ecosystems: Its dense canopy drastically reduces light availability to the understorey, changing the composition and structure of native plant communities. It also consumes significant water resources.
Outcompeting indigenous vegetation: Its rapid growth rate, high seed production, bird dispersal, and ability to thrive in various conditions allow it to outcompete and displace native flora, leading to a dramatic reduction in biodiversity.
Impacting fynbos and forest ecosystems: It is particularly problematic in fynbos where it transforms open shrublands into dense woody stands, and in forest margins where it pushes out native forest species.
Prolific seed production and bird dispersal: The sticky seeds are highly attractive to and effectively dispersed by birds, facilitating its widespread invasion into pristine areas.
Distribution and habitat:
In South Africa, Pittosporum undulatum is widely distributed and highly invasive, particularly in the Western Cape, Eastern Cape, KwaZulu-Natal, Mpumalanga, and Gauteng. It commonly invades forest margins, woodlands, fynbos, grasslands, coastal areas, roadsides, and disturbed sites, especially in higher rainfall regions.
Derivation of name:
The genus name Pittosporum comes from Greek: "pitta" (pitch or resin) and "sporos" (seed), referring to the sticky resinous coating on the seeds.
The species name undulatum is Latin for "wavy" or "undulating," referring to the distinctive wavy margins of its leaves.
Common names like "Sweet Pittosporum" refer to the intense fragrance of its flowers. "Australian Cheesewood" refers to its origin and a perceived resemblance of its wood to cheesewood.
Historical aspects:
Pittosporum undulatum was introduced to South Africa as an ornamental garden plant in the mid-19th century, prized for its evergreen foliage, dense growth, and highly fragrant flowers. Its popularity and ease of cultivation led to its widespread planting in urban and suburban areas. However, its aggressive invasive nature, facilitated by prolific seed production and bird dispersal, soon became apparent, leading to its classification as a declared invasive species. It is now subject to control efforts to mitigate its severe ecological impact, particularly in sensitive fynbos and forest ecosystems.
Interesting facts:
This plant smells amazing! Its creamy-white flowers have a super sweet, orange-blossom-like scent that's particularly strong at night. It's like a natural perfume factory!
Its name, "Pittosporum," actually means "pitch seed" because its seeds are coated in a super sticky, resinous goo. This stickiness is cleverly designed to make the seeds cling to birds, helping them spread far and wide!
While it looks beautiful, this plant is a bit of a bully. It grows incredibly fast and forms dense thickets that completely block out sunlight, making it impossible for native plants to survive underneath.
You can easily spot it by its glossy, dark green leaves that have distinctively wavy edges, like ripples in water. It's a key identifier of this fragrant invader.
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