Eucalypts
What are they?
The Gum Trees or Eucalypts are a southern hemisphere group of plants. Although their overall range extends as far as Indonesia and New Guinea, Eucalypts will always be most strongly associated with Australia, along with Koalas, billabongs and didgeridoos! This genus of plants includes some of the world's tallest broadleaved trees and produce remarkably hard and durable wood which is much favoured by the mining industry to provide material for supporting pit props. To supply demand, these trees have been planted throughout the world, but have proven to set seed and flourish and often create ecological difficulties for land management and conservation. In the UK, Eucalypts are not so prolific but do occasionally self seed. The petalless flowers with many stamens are typical of the myrtle family (Myrtaceae) to which they belong.
Where are they found?
Eucalypts are popular as garden ornamentals, as well as for fast-growing shelter belts and screening. Although they are only rarely found as garden throw-outs or where self-sown, these trees may frequently be encountered in shelter belts and hedgelines or urban open spaces.
Identification
The typically blue-green or blue-grey colour of the evergreen leaves and tell-tale Eucalyptus smell readily gives the identity of this group away. However, identification to species can be difficult and relies on the details of a suite characters, which may need to be gathered from more than one visit. The number of flowers and their arrangement in each cluster should be noted (this can be assessed from the dry seed capsules which stay on the tree for several years so the plant does not need to be in flower - though be aware that not all flowers will form capsules so the count is less reliable this way). In addition, note the bark detail, as well as leaf shape and typical length (including both leaf types if present (Eucalypts have so-called juvenile foliage when they are young which tends to produce leaves that are shorter and rounder than those on mature growths).
Cider Gum Eucalyptus gunnii
Introduced from Tasmania. Very common as an amenity and garden tree and occasionally found as odd specimens in hedgerows and shelter belts. A tree growing to 25 metres in height but often kept lower by pruning to produce continuous, juvenile foliage. Juvenile leaves in opposite pairs, rounded and together more or less encircling the stem. Adult leaves to 4.5cm in length and with a spicy, curry-like smell. Flowers in groups of three in the leaf axils. Bark mostly smooth, pale grey on younger bark, slightly greenish on older strips; sometimes rough at the base of the trunk.
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Shining Gum Eucalyptus nitens
Introduced from SE Australia. Rare, but noticed as a shelter belt tree in several places in 2019, while a grove of mature trees also exists just east of Diss. A tree growing to 25 metres but may reach 90 metres! Juvenile leaves in opposite pairs, to 10cm in length and encircling the stem at their base. Adult leaves to 24cm in length, alternate, willow-like or sickle-shaped, dark glaucous-green and distinctly shiny. Flowers stalkless, in distinctive whorls of five with a sixth at right angles to the whorl. Bark mostly smooth, pale grey on younger bark, but often partially hidden behind a layer of older bark that hangs in very long, tattered shreds.
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Alpine Ash Eucalyptus delegatensis
Introduced from SE Australia. Rare as an amenity in parks and churchyards. A tree growing to some 40 metres but may be shorter and multi-stemmed. Juvenile leaves alternate, dull green and just a little shorter and broader than adult leaves. Adult leaves to 22cm in length, alternate, shining, glaucous-green. Flowers in stalked umbels of five to over 20 together, distinctly elongated and warty. Bark grey or greenish lower down, creamy white higher up.
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