Trees of the Year 2001

Rare Tree: Sneezewood

National Tree Number:
Botanical name: Ptaeroxylon obliquum
Other names: Nieshout, umThathi (Xhosa)

Description:
Plants are easily identified by opposite leaves, with three to eight pairs of dark green leaflets, including a terminal pair at the end of the leaf. Leaflets are distinctly asymmetrical in shape. Flowers are small, sweetly scented, white and produced from August to December. Male and female flowers occur on different trees. The fruit is an oblong capsule, notched at the tip and split open to produce winged seeds. ¹⁾

A large tree of up to 20m; variable in habitat, size and colour (small in low bushveld; large in mistbelt mountain forests; also occurs in coastal and sand forests).

General:
Ptaeroxylon is a direct Greek translation meaning sneeze and wood; obliquum refer to the oblique leaflets.

A small genus with only one species. Until recently this and the Madagascar Cedrelopsis were placed in a family of their own, Ptaeroxylaceae, but DNA sequences and chemical evidence leave little doubt that this belongs to the large citrus family Rutaceae. Noteworthy, the Common Citrus Swallowtail butterfly Papilio demodocus is known to visit and breed on this tree. Other indigenous trees in the family recommended for the garden are the Cape-chestnut, white-ironwood and the small knobwood. ¹⁾

Uses:
Sneezewood is extremely hard and durable and highly valued as a timber for fence post and buildings. Little furniture was ever made of it, but with some effort and preparation beautiful pieces can be made.

Highly irritant aromatic peppery oils, containing nieshoutol are produced, causing violent sneezing by woodworkers after sawing or sanding.

When used as machine bearings Sneezewood often wears longer than brass or iron. In Mozambique it is the preferred wood for the manufacture of xylophone keys. ¹⁾

Distribution:
The distribution of this species extends to tropical Africa. ¹⁾

Cultivation:
Seed, if not damaged by insects, is easy to germinate. A moderate to fast grower (0.4 to 1 m per year). It will withstand moderate frost and is very drought-tolerant.