Eucalyptus gregsoniana, Wolgan Snow Gum is a tall shrub or small tree reaching a height of six metres, often seen as a mallee.
It is found only in NSW, in two generally disjunct areas; immediately north and east of Lithgow and extending through the Blue Mountains to Lithgow; then on the southern tablelands, near Mongarlowe and Braidwood and extending north, to between Tarago and Nerriga, and as far south as east of Cooma (Wadbilliga State Forest).
It typically grows in dry sclerophyll woodlands on moist sandy soils.
The bark is smooth, white or grey and shed in ribbons.
Eucalyptus spp. have simple and usually alternate adult leaves with juvenile leaves starting off opposite to alternate (disjunct). In this species, juvenile leaves are grey-green, lanceolate to falcate, to 13 cm long and 4.5 cm wide. Adult leaves are 10 cm long and 2.5 centimetres wide, lanceolate, leathery and grey-green on both surfaces. The minor veins of leaves are almost parallel with the prominent mid vein – a useful identifying feature.
The primary inflorescence of “eucalypts” (Angophora / Corymbia / Eucalyptus) is an umbellaster (an umbel-like cluster of flowers). In the flowers of Corymbia and Eucalyptus, the petals and sepals are fused into the distinctive calyptra / operculum (bud cap) which is shed when the flower opens (in some species, 2 bud caps (opercula) are shed). The flowers are conspicuously staminate – where many stamens are basically taking over the role of the petals, all surrounding one central carpel. In this species, flowers are carried in umbellasters of 7-11. Flowers are 1 cm across, white and appear in spring.
The fruit of eucalypts are a woody capsule (commonly called ‘gum nuts’) which come in a wide variety of shapes with the top part having a sunken, flat or raised disc and with the valves inserted, disc-level, exserted to strongly exserted. In this species, capsules are pear-shaped or globular, to about 9 mm long and wide, with 3 to 4 valves at or near rim level.
This species reportedly does well in cultivation. Once established, it needs little care and maintenance and does not grow overly large. Flowers will attract birds and bees. Cultivated specimens usually confine themselves to a single trunk.
Give good drainage in a sandy to loam soil. It may suffer if it gets wet feet. It can be pruned to create a mallee habit and does flower quickly.
Propagate from seed.
There is reportedly a specimen of this species growing outside in Kew Gardens, UK.
This species can regenerate from the lignotuber after fire. It can also regenerate from seed.
It is well-known that Eucalyptus is a large and diverse genus. Between 700 and 950 known species are reported, occurring as far north as The Philippines, as well as Indonesia, New Guinea, Timor and Australia. Only 16 species reportedly occur outside Australia. They occur in all Australian states. NSW currently has about 250 species. (See this website for some detailed information: https://apps.lucidcentral.org/euclid/text/intro/learn.htm).
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).
gregsonii – named in 1973 in Honour of Edward Gregson – an amateur botanist who lived in the Blue Mountains area of NSW. His father, Jesse Gregson (1837-1919) was a superintendent of the Australian Agricultural Company and a keen amateur botanist and plant collector. There are reports that the species is named for both people.
This species is not considered to be at risk of extinction in the wild.
Australian National Herbarium – Eucalyptus gregsoniana profile page https://www.anbg.gov.au/gnp/interns-2012/eucalyptus-gregsoniana.html
NSW Flora Online (PlantNET) – Eucalyptus gregsoniana profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~gregsoniana
Specialty Trees – Eucalyptus gregsoniana sales page https://www.specialitytrees.com.au/trees/eucalyptus-gregsoniana-zm17q