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Eucalyptus olsenii

Woila Gum

Family: Myrtaceae

Eucalyptus olsenii is known as the Woila Gum and grows into a tree reaching 12 metres in height.

The bark is rough on the lower part of the trunk whilst the rest of the trunk and branches are smooth, white, cream or grey. Leaves may be lance-like or curved, up to 12 centimetres long, two centimetres wide and glossy green. Buds are carried in clusters of seven and have distinctive ribs or ridges.

Large white flowers are carried in spring and summer. The woody fruits, that follow the flowers, are barrel or urn-shaped and two centimetres long.

Eucalyptus olsenii is considered a rare species (but not threatened) because it has a restricted range. All known populations are protected in two national parks, Deua and Wadbilliga on the Southern Tablelands of New South Wales.

In the garden

In our cold climate garden, E. olsenii has proved tolerant of drought and frost, fast growing and free flowering. Our specimen flowered for the first time about four years after planting. 

It is not widely planted but has attractive fruit, flowers and flower buds; and can likely be kept at less than 10 m tall in any garden through pruning. It grows naturally on sandy-rocky situations and so likely needs good drainage to thrive. 

Propagation

Propagate from seed

Other information

The common name refers to Mother Woila Mountain and Woila Creek, both locations in Deua National Park.

This species likely regenerates from the seed bank after fire. It may also produce epicormic shoots. 

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).

olsenii – named after Ian Sinclair Olsen (b. 1943) who was a landscape designer at the Royal Botanic Gardens, Sydney and who has collected many plant specimens whilst bushwalking – in NSW, but also, Tasmania, Qld and SA. Olsen was the first to collect this species. 

This species is not considered to be at risk of extinction in the wild but is considered rare with a limited natural distribution. 

NSW Flora Online (PlantNET) – Eucalyptus olsenii profile page                                                            https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~olsenii

EUCLID – Eucalypts of Australia – Centre for Australian National Biodiversity Research – Eucalyptus olsenii profile page                                        https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_olsenii.htm 

Wikipedia – Eucalyptus olsenii profile page                                https://en.wikipedia.org/wiki/Eucalyptus_olsenii

By Warren and Gloria Sheather