Eucalyptus camaldulensis (river red gum)

River red gum is widespread in south-eastern Australia and southern Queensland. It is also widely cultivated, mainly in Europe and Asia, but also in California (USA), British Guiana, Venezuela, Bolivia and Africa. 

A population of E. camaldulensis in native site (Image: Pavel Buršík, Copyright:  Some rights reserved)

A medium-sized tree, generally growing up to 30 metres tall (but can sometimes become a large tree of up to 45 m), with a thick trunk covered with peeling bark. The smooth bark can be grey, pinkish grey, white or brown. The leaves are mostly alternate (one at each node), lance-shaped to narrowly so, 18–25 × 2 cm. The leaves are green or bluish green, usually the same colour on each side of the leaf, dull or glossy, with oil glands seen clearly. The inflorescence is axillary, with 7–11 white flowers with pedicels (flower stalks) of about 2.5 cm long. The buds have a scar, and the bud caps are strongly beaked or conical. The stamens (male parts of the flower) are inflexed (bent inward or downward) or erect. The fruit is hemispherical, 0.6 × 1 cm, and contains yellow to yellow-brown seeds with a terminal hilum (scar indicating the point of attachment).

Eucalyptus camaldulensis is one of several Eucalyptus species which is invasive in South Africa. Australia and South Africa share similar environmental conditions, and hence species that grow well in one are likely to do so in the other. River red gum, although in balance with other organisms in its native environment has caused much damage to South African landscapes where it has been introduced and become invasive. Long stretches of rivers and dam shores have been transformed by river red gum. It draws up a large amount of water from the ground, contributes to soil erosion and adversely affects nutrient cycling and soil properties.

Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in the seed bank vault.

Description of seeds: Average 1,000 seed weight = 2.4 g.
Number of seed collections stored in the Millennium Seed Bank: Six.
Seed storage behaviour: Orthodox (the seeds of this plant survive being dried without significantly reducing their viability, and are therefore amenable to long-term frozen storage such as at the MSB)
Germination testing: 98% germination was achieved with: germination medium = 1% agar; germination conditions = 20°C, 8/16. 98% germination was achieved with: germination medium = 1% agar; germination conditions = 10°C, 8/16. 91% germination was achieved with: germination medium = 1% agar; germination conditions = 15°C, 8/16.

Dried herbarium specimen of Eucalyptus camaldulensis collected in Australia (Image: RBG Kew)

Pressed and dried specimens of river red gum are held in the Herbarium, one of the behind-the-scenes areas of Kew. The details, including images, of some of these can be seen in the on-line Herbarium Catalogue.

Specimens of river red gum bark, oil, fruits, resin and wood are held in the behind-the-scenes Economic Botany Collection.

More about the artist Hans Heyven

Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL)

Plant Resources of Tropical Africa (PROTA)