The family Heteropyxidaceae, or lavender tree family as it is commonly known, is a small family with only two species in southern Africa. The local genus, Heteropyxis, is characterized by alternate, entire, simple leaves with secretory cavities. These emit a pleasant smell when crushed. The flowers are small and inconspicuous.

The genus name of this plant (Heteropyxis) is made up of two words. Hetero is a Greek word meaning 'different' and pyxis is a Latin word meaning 'the container with the lid'. This refers to the capsule (a fruit) that is sometimes called the pyxidium, because it looks like it has a lid. The species name natalensis refers to its place of origin, KwaZulu-Natal.

This is a medium to large deciduous tree that grows to about 10 metres high. It occurs naturally on the coastal and inland regions of the KwaZulu-Natal Province. It is also found growing in Mpumalanga, Gauteng, Swaziland and Zimbabwe.

The lavender tree has drooping foliage. The leaves are narrowly elliptic and are arranged spirally. They are shiny dark green above and paler green below, slightly hairy to hairless when mature. When crushed they produce a strong lavender scent. The leaf petiole is slender and pink over the lower half.

The main stem is crooked and sometimes fluted. The bark is distinctively pale grey, often almost white and is flaking on the old stem. The flowers, which are yellowish green, appear in summer (December - March). They are very small, about 3 mm in diameter, and are borne in branched terminal clusters. They are sweetly scented. The fruit is a small oval capsule that is up to 4 x 2.5 mm. It appears between March and May. Its colour is shiny brown and it bears numerous seeds. When ready, it splits into 2 to 3 valves releasing the seeds, after which the old capsules may remain on the tree for months.

This tree has several economic uses. Bark and leaves are browsed by black rhino. Leaves are also used in herbal tea and potpourri. The wood is hard, very fine grained and is pale pinkish brown in colour. It is suitable for use as fencing posts and charcoal. The leaves and roots of this plant are used medicinally and to treat worms in stock. African healers prescribe inhaling the steam from a decoction of the roots to heal a bleeding nose. The roots are also used in the treatment of mental disorders and fresh leaves are used during weaning. The leaves are also used to scent tobacco.

Growing Heteropyxis natalensis

The lavender tree can be grown from seeds. They germinate easily and the young plants are relatively quick growing. Sow the seeds in well-drained moist soil and cover them with a thin layer of compost. Make sure they are kept in a warm area as this promotes rapid germination. This plant can also be propagated by cuttings, although the success rate using this method is very low. Fresh cuttings may be taken and rooted in pure sand. Rooting hormone may be used to help promote rooting.

Heteropyxis natalensis is a very decorative tree for small gardens. With its glossy green leaves and a whitish stem, it makes a very good focal point. The leaves develop rich red autumn colours, adding to the tree's attractiveness. The flowers attract bees, wasps and butterflies.

References

• Palgrave, K. C. 1997. Trees of Southern Africa, C. Struik Publishers: Cape Town.
• Pooley, E. 1993. Trees of Natal Zululand & Transkei, Natal Flora Publication Trust: Durban.
• Van Wyk, B. and Van Wyk, P., 1997. Field Guide to Trees of Southern Africa, Struik Publishers: Cape Town.
• Hutchings, A. 1996. Zulu Medicinal Plants, University of Natal Press: Pietermaritzburg.

Mhlonishwa D Dlamini & Andrew Hankey
Witwatersrand National Botanical Gardens
June 2002