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Eucalyptus steedmanii

Steedmans Mallet, Steedmans Gum

Family: Myrtaceae

Eucalyptus steedmanii is a mallet-eucalypt, growing to a height of 10 metres, spreading to 7 metres wide (larger in favourable conditions).

It is endemic to a very small area of south-west Western Australia, naturally found several hundred kilometres east of Perth, in the Forrestania to North Ironcap areas, where there are at least 6 known populations.

It grows on gravelly loams over ironstone on undulating plains, forming part of mallet-shrublands.

It is listed as being threatened with extinction in the wild.

This species has the classic “mallet” character – small-fluted branching tree with spreading dense crown. The bark is smooth with a satin appearance, grey to red-brown to bright-copper in colour.

Leaves are to 8 cm long (comparatively short), linear to narrowly-lanceolate, concolorous, glossy olive-green with numerous oil glands.

The flower buds are arranged in groups (umbellasters) of 3s on pendulous flatten peduncles. The buds are square, longitudinally winged and feature 4 retained sepals on the split outer operculum (the operculum splits open rather than being shed). The inner operculum (made up of fused petals) is pyramidal. The flowers are white-staminate, occurring from January to March.

The capsules have pedicels to 2 cm long and are square to conical and winged (about 2 x 2 cm), with a thick rim and level disc, with 4 exserted valves. Seeds are dark grey-brown.

In the garden

A hardy species which will grow in a wide range of soils, with varying pH conditions. It will also tolerate a range of climates. Drought resistant and tolerant of moderate frost conditions. Likes sunny open environments where it will grow to a handsome feature tree.

Provided this small mallet is given a sunny aspect with sufficient space (50 square metres recommended), it will grow to its full potential providing excellent shade and screening properties. It can be used in windbreaks

if combined with a low shrub layer (preferable a legume to facilitate nitrogen cycling).

It has no common pest or disease issues. However, humid environments are unfavourable.

A low maintenance plant which can be trained to hedge if pruned early. The hedge, however, will require regular pruning.

Propagation

From seed.

Other information

This species does not form a lignotuber. Fire is listed as a key threat to natural populations which has been observed to kill adult trees. Regeneration is mainly from seed.

Eucalyptus – from Greek, eu, “well” or “true” and calyptus, referring to the calyptra (καλύπτρo) or operculum, which is a bud cap or covering which covers the developing flowers. The calyptra is a fusion of petals and/or sepals and is shed when the flower opens, leaving a flower with many stamens (staminate) surrounding one female part (carpel).

steedmanii – named in Honour of Henry Steedman (c. 1866 – 1953) (who collected a specimen from near Southern Cross in 1928), by Charles Gardner in 1933. Steedman was head gardener at the South Perth Zoological Gardens. He devoted himself to collecting native plants and seeds and was responsible for introducing many new plants to science.

This species is listed as being threatened with extinction in the wild under the Commonwealth EPBC Act (category of Vulnerable).Brooker M & Kleinig D (1990).

Field Guide to Eucalypts South-western & Southern Australia. Inkata Press, Melb.

Elliot R & Jones D (1986). Encyclopaedia of Australian Plants Vol 4, Lothian, Melb.

Euclid: Centre for Australian National Biodiversity Research – Eucalyptus steedmanii profile page  https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_steedmanii.htm

Approved Conservation Advice Eucalyptus steedmanii (s266B of the Environment Protection and Biodiversity Conservation Act 1999). Australian Government – Department of the Environment, water Heritage and the Arts.

Florabase – Western Australian Herbarium – Eucalyptus steedmanii profile page
https://florabase.dpaw.wa.gov.au/browse/profile/5777

By Andrew Knop,