Elaeodendron croceum

Fruit of E. croceum

Elaeodendron croceum is an attractive, evergreen tree with a neat, upright shape which can with care be cultivated in gardens large and small.

Description
This evergreen tree is medium to tall with a neat, upright shape. The bark is grayish, with a conspicuous layer of a powdery yellow pigment in the freshly exposed bark. Branches are grayish brown with prominent, coarse black lenticels. Leaves are opposite, hard and leathery with the venation inconspicuous, lamina elliptic, dark green, between 15 mm to over 200 mm long; the base and apex are sharp-pointed, the margin is prominently spine-tipped, especially on young shoots; the petiole is 4-10 mm long with a small triangular stipule.

Flowers of E croceum The inflorescences are tiny; consisting of 3 to 15 flowers. Flowers are in four parts, about 3 mm in diameter. Sepals and petals are green and white respectively and with an ovate shape. The stamens are erect to spreading, on a 0.5 mm short filament. A flat, prominent disc surrounds the 2-locular, round ovary, with an inconspicuous style and stigma. The fruit is cream-coloured, 20 to 30 mm long, and the small seed is enclosed by a hard, pointed stone or putamen, like that of an olive.

Distribution and habitat
Elaeodendron croceum presently occurs from near Ladismith in the west to northern KwaZulu-Natal, as well as on the escarpments of Limpopo and Mount Cherinda in Zimbabwe. However, it is most frequent in the southern Cape forests. It was also once recorded from St Helena, but this could be attributed to the establishment of plantations of this tree by early colonists. Mellis (1875) considered this tree (which he called wild olive) as very common and 'one of the handsomest trees on the island'.

In its ideal habitat Elaeodendron croceum occurs on the margins of coastal and other moist inland forests. In wet conditions the outer portion of the bark breaks off more frequently, exposing the characteristic yellow pigments that the species shares with other Celastraceae such as Cassine peragua and Pterocelastrus echinatus. The yellow bark is then remarkably conspicuous.

Derivation of name and historical aspects
The Celastraceae is a large and rather diverse family distributed in the tropical and temperate zones of the world. Most of its species have been subject to considerable nomenclatural confusion and name changes. Since the species was described by Carl Peter Thunberg (1794) as Ilex crocea, it has been treated under several species names within Elaeodendron or Cassine. The common names have also been a source of confusion.

Thunberg encountered the species near the Grootvadersbosch near Swellendam in October 1774. He described the species as follows: 'Yellow wood (Geelhout, Ilex crocea) is of a yellow colour, almost like box, of a close texture, and handsome. It is used for planks and beams in the construction of houses, for tables, doors, cupboards, window frames, and butter churns'. His description of the wood is entirely correct but it is probably not as widely used as the yellowwood derived from the two species of Podocarpus also present in the Grootvadersbosch (with the possible exception of butter churns that have been reported as being made from wood of Elaeodendron croceum). This forest was an important source of timber for Cape Town at the time but Thunberg evidently confused the uses of this yellow wood with that of Podocarpus species.

The common names recorded by Thunberg are reflected in his name: croceum means 'saffron yellow'. This colour is present as bright yellow pigment in the bark of many species of the family Celastraceae, including Elaeodendron croceum. Ecklon & Zeyher (1834) gave a literal translation of saffron wood when they proposed the synonymous generic name Crocoxylon. Other names that are synonyms for Elaeodendron croceum include: Crocoxylon excelsum; Cassine crocea, Elaeodendron capense and until recently Cassine papillosa.

The name of the genus Elaeodendron is derived from the Mauritius tree, Bois d'Olive (or olive tree), after the resemblance of the fruit to the true olive was noted by the first scientist collecting this tree.

Uses and cultural aspects
It is difficult to establish the extent of use of the wood of this species due to the confusion of its names with that of Podocarpus species. But the wood is of fine quality with a beautiful golden lustre, well suited for fine furniture. Unfortunately it is rarely available in the timber trade. Preparations of the root and bark have proved to be fatal to humans, presumably due to the presence of alkaloids of which little is known. The bark was used in dyeing and tanning by Voortrekker settlers (Watt & Breyer-Brandwijk 1962). This is an attractive tree for horticuiltutral use and a species with unusual variation in the leaves can be seen in Kirstenbosch National Botanical Garden.

Variegated leaves on tree in Kirstenbosch

Growing Elaeodendron croceum

This species grows easily from seed and from cuttings, but is usually not a fast grower. If the stone covering of the seed is not removed or broken, germination can take anything from 12 to 30 months. Young plants tend to grow very slowly or remain straggly for a long period, but this could be an adaptation to forest conditions where sun and space are limited. Once a space is created by an old fallen tree, the young seedlings can take its place.

References and further reading

Archer, R.H. 1995. Elaeodendron croceum. Flowering plants of Africa 54: 58-62.
Archer, R.H. & Van Wyk, A.E. 1998. A taxonomic revision of Elaeodendron Jacq.
(Celastraceae). South African Journal of Botany 64: 93-109.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, edn 3. Struik, Cape Town.
Mellis, J.C. 1875. St. Helena. Reeve, London.
Watt, J.M. & Breyer-Brandwijk, M.G. 1962. The medicinal and poisonous plants of southern and eastern Africa, edn 2. Livingstone, Edinburgh.

Author
Robert H. Archer
National Herbarium, Pretoria
June 2004