Snow Gum

''Eucalyptus pauciflora'', commonly known as snow gum, cabbage gum or white sally, is a species of tree or mallee that is native to eastern Australia. It has smooth bark, lance-shaped to elliptical leaves, flower buds in clusters of between seven and fifteen, white flowers and cup-shaped, conical or hemispherical fruit. It is widespread and locally common in woodland in cold sites above altitude.

Description

''Eucalyptus pauciflora'' is a tree or mallee, that typically grows to a height of and forms a lignotuber. It has smooth white, grey or yellow bark that is shed in ribbons and sometimes has insect scribbles. Young plants and coppice regrowth have dull, bluish green or glaucous, broadly lance-shaped to egg-shaped leaves that are long and wide. Adult leaves are the same shade of glossy green on both sides, lance-shaped to curved or elliptical, long and wide, tapering to a petiole long. The flower buds are arranged in leaf axils in cluster of between seven and fifteen, sometimes more, on an unbranched peduncle long, the individual buds on pedicels up to long. Mature buds are oval, long and wide with a conical to rounded operculum. Flowering occurs from October to February and the flowers are white. The fruit is a woody, cup-shaped, conical or hemispherical capsule long and wide.

Taxonomy

''Eucalyptus pauciflora'' was first formally described in 1827 by Kurt Polycarp Joachim Sprengel from an unpublished description by Franz Sieber. Sprengel published the description in '' Systema Vegetabilium''. The specific epithet ''pauciflora'' is from the Latin ''pauciflorus'' meaning "few-flowered". The term ''pauciflora'' (few-flowered) is a misnomer, and may originate in an early collected specimen losing its buds in transit.

Six subspecies are recognised by the Australian Plant Census as at 30 November 2019:
* ''Eucalyptus pauciflora'' subsp. ''acerina'' Rule occurs in Victoria;
* ''Eucalyptus pauciflora'' subsp. ''debeuzevillei'' (Maiden) L.A.S.Johnson & Blaxell in Victoria, New South Wales and the Australian Capital Territory;
* ''Eucalyptus pauciflora'' subsp. ''hedraia'' Rule in Victoria;
* ''Eucalyptus pauciflora'' subsp. ''niphophila'' (Maiden & Blakely) L.A.S.Johnson & Blaxell in New South Wales, the Australian Capital Territory and Victoria;
* ''Eucalyptus pauciflora'' subsp. ''parvifructa'' Rule in Victoria;
* ''Eucalyptus pauciflora'' Sieber ex Spreng. subsp. ''pauciflora'' is found in Queensland, New South Wales, the Australian Capital Territory, Victoria, South Australia and Tasmania.

Distribution and habitat

Snow gum grows in woodland along the ranges and tablelands, in flat, cold sites above from the far south-east of Queensland, through New South Wales, the Australian Capital Territory, and Victoria, to near Mount Gambier in South Australia and Tasmania.

In Tasmania the species hybridises with '' Eucalyptus coccifera'' and '' Eucalyptus amygdalina''.

Ecology

Snow gum is amongst the hardiest of all eucalyptus species, surviving the severe winter temperatures of the Australian Alps. The species regenerates from seed, by epicormic shoots below the bark, and from lignotubers. It is the most cold-tolerant species of eucalyptus, with ''E. pauciflora'' subsp. ''niphophila'' surviving temperatures down to and year-round frosts. It has been introduced to Norway.

Influence on snowpack processes

At altitudes where stands of snow gum coincide with seasonal snowfall above an altitude of about , the trees have been shown to increase snowpack accumulation and moderate melt, making snow gum critically important to the hydrology and water resources of southeast Australia. Contrary to characteristics of needle-leaf forests, snow gums don't frequently intercept large quantities of snowfall on branches and leaves such that increased evaporation or sublimation would occur. As a result, snow accumulation is greater in living snow gum forests than burned forests or unforested areas.

Bushfire impact on snow gums alters these effects and leads to reduced snowpack longevity and greater evaporation/sublimation processes, in turn reducing snowpack runoff available for ecosystem and human use. It is estimated that the 2019-2020 bushfires impacted 462 km² (33%) of mapped snow gum forest that regularly has seasonal snowpack, which would equate to a reduction in annual snowpack runoff of 63.3 gigalitres (about 25,320 olympic swimming pools).

Use in horticulture

In cultivation in the UK, ''Eucalyptus pauciflora'' subsp. ''niphophila'' and ''Eucalyptus pauciflora'' subsp.
''debeuzevillei'' have gained the Royal Horticultural Society's Award of Garden Merit.

Gallery

Image:Snow Gum Tree.jpg, A snowgum at Perisher in New South Wales
Image:Snow Gum1.JPG, Image showing the tree's ability to survive in deep snow
Image:Snow Gum 2.JPG, Image showing how the branches bend rather than break with the weight of the snow and how this causes snow to be lost from the leaves
Image:Stillwell from Pulpit.jpg, Snow gum woodland below the tree line

References

Further reading

* Iglesias Trabado, Gustavo (2007). ''Eucalyptus'' from Alpine Australia. Notes on taxonomy and cultivation in cold temperate climates, In
EUCALYPTOLOGICS

External links

{{Taxonbar, from=Q2165298

pauciflora
Myrtales of Australia
Flora of the Australian Capital Territory
Flora of New South Wales
Flora of Queensland
Flora of Tasmania
Flora of Victoria (state)
Flora of South Australia
Trees of Australia
Trees of mild maritime climate
Plants described in 1827