Lemon-scented gum | |
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In Wagga Wagga Botanic Gardens | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Myrtales |
Family: | Myrtaceae |
Genus: | Corymbia |
Species: | C. citriodora |
Binomial name | |
Corymbia citriodora | |
Synonyms [1] | |
List
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Corymbia citriodora, commonly known as lemon-scented gum [2] and other common names, [3] [4] is a species of tall tree that is endemic to north-eastern Australia. It has smooth white to pink bark, narrow lance-shaped to curved adult leaves, flower buds in groups of three, white flowers and urn-shaped or barrel-shaped fruit.
Corymbia citriodora is a tree that typically grows to a height of 25–40 m (82–131 ft), sometimes to 50 m (160 ft) and forms a lignotuber. It has smooth, pale, uniform or slightly mottled, white to pink or coppery bark that is shed in thin flakes. Young plants and coppice regrowth have egg-shaped to lance-shaped leaves that are 80–210 mm (3.1–8.3 in) long and 32–80 mm (1.3–3.1 in) wide. Adult leaves are the same shade of glossy green on both sides, often lemon-scented when crushed, narrow lance-shaped to curved, 100–230 mm (3.9–9.1 in) long and 6–28 mm (0.24–1.10 in) wide tapering to a petiole 10–25 mm (0.4–1.0 in) long. The flower buds are borne in leaf axils on a branched peduncle 3–10 mm (0.1–0.4 in) long, each branch with three buds on pedicels 1–6 mm (0.04–0.24 in) long. Mature buds are oval to pear-shaped, 6–10 mm (0.24–0.39 in) long and 5–7 mm (0.20–0.28 in) wide with a rounded, conical or slightly beaked operculum. Flowering occurs in most months and the flowers are white. The fruit is a woody urn-shaped or barrel-shaped capsule 8–15 mm (0.31–0.59 in) long and 7–12 mm (0.28–0.47 in) wide with the valves enclosed in the fruit. [2] [5] [6] [7] [8]
Lemon-scented gum was first formally described in 1848 by William Jackson Hooker, who gave it the name Eucalyptus citriodora in Thomas Mitchell's Journal of an Expedition into the Interior of Tropical Australia. [9] [10] In 1995 Ken Hill and Lawrie Johnson changed the name from Eucalyptus citriodora to Corymbia citriodora. [5] [11] The specific epithet (citriodora) is Latin, meaning 'lemon-scented'. [2]
Lemon-scented gum is also commonly known as citron-scented gum, lemon gum, spotted gum [3] and lemon eucalyptus. [4]
Corymbia citriodora is similar to C. maculata and C. henryi . [2]
Some naturalists and conservationists do not recognise the genus Corymbia and still categorise its species within Eucalyptus . [12]
Corymbia citriodora grows in undulating country in open forest and woodland in several disjunct areas in Queensland and as far south as Coffs Harbour in New South Wales. In Queensland it is found as far north as Lakeland Downs and Cooktown and as far inland as Hughenden and Chinchilla. [2] [6]
Kings Park in Perth has an avenue of this species planted many years ago, but the species has spread to become an environmental weed in the Sydney and Blue Mountains region in New South Wales and in open woodland areas in the south-west of Western Australia. [3] [13]
The essential oil of the lemon-scented gum mainly consists of citronellal (80%), [14] produced largely in Brazil and China. [15] Unrefined oil from the lemon eucalyptus tree is used in perfumery, and a refined form of this oil is used in insect repellents, especially against mosquitoes. The refined oil's citronellal content is turned into cis- and trans- isomers of p-menthane-3,8-diol (PMD), a process which occurs naturally as the eucalyptus leaves age. This refined oil, which includes related compounds from the essential corymbia citriodora, is known widely by its registered tradename, "Citrepel" or "Citriodiol", but also by generic names which vary by region: "oil of lemon eucalyptus" or "OLE" (USA); "PMD rich botanic oil" or "PMDRBO" (Europe); "PMD and related oil of lemon eucalyptus compounds" (Canada); Extract of Lemon Eucalyptus (Australia). Pure PMD is synthesized for commercial production from synthetic citronellal. Essential oil refined from the leaves of the tree can contain up to 98% citronella content. The smell of the essential oil can vary, but mostly includes a strong odor comparable alone to citronella oil, with a slight hint of lemon scent.[ citation needed ]
A study comparing mosquito repellents found that products using the oil of lemon eucalyptus were effective at driving mosquitos away from a human hand. [16]
Corymbia ficifolia, commonly known as red flowering gum, is a species of small tree that is endemic to the south-west of Western Australia. It has rough, fibrous bark on the trunk and branches, egg-shaped to broadly lance-shape adult leaves, flower buds in groups of seven, bright red, pink or orange flowers and urn-shaped fruit. It has a restricted distribution in the wild but is one of the most commonly planted ornamental eucalypts.
Citronella oil is an essential oil obtained from the leaves and stems of different species of Cymbopogon (lemongrass). The oil is used extensively as a source of perfumery chemicals such as citronellal, citronellol, and geraniol. These chemicals find extensive use in soap, candles and incense, perfumery, cosmetic, and flavouring industries throughout the world.
An insect repellent is a substance applied to the skin, clothing, or other surfaces to discourage insects from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne diseases such as malaria, Lyme disease, dengue fever, bubonic plague, river blindness, and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as flea, fly, and mosquito; and ticks (arachnids).
Citronellal or rhodinal (C10H18O) is a monoterpenoid aldehyde, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent.
Backhousia citriodora, commonly known as lemon myrtle, lemon scented myrtle or lemon scented ironwood, is a flowering plant in the family Myrtaceae. It is endemic to subtropical rainforests of central and south-eastern Queensland, Australia, with a natural distribution from Mackay to Brisbane.
Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus, a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, antiseptic, repellent, flavouring, fragrance and industrial uses. The leaves of selected Eucalyptus species are steam distilled to extract eucalyptus oil.
Eucalyptus staigeriana, commonly known as the lemon-scented ironbark, is a species of small ironbark tree that is endemic to the Cape York Peninsula. It has rough ironbark on the trunk and branches, lance-shaped to egg-shaped leaves that smell of lemons when crushed, flower buds in groups of seven, white flowers and oval to spindle-shaped fruit.
Angophora costata, commonly known as Sydney red gum, rusty gum or smooth-barked apple, is a species of tree that is endemic to eastern Australia. Reaching 30 m (100 ft) in height, the species has distinctive smooth bark that is pinkish or orange-brown when new and fades to grey with age. Its lance-shaped leaves are arranged in opposite pairs along the stems, with white or creamy white flowers appearing from October to December. The flower buds are usually arranged in groups of three, followed by ribbed, oval or bell-shaped fruit.
Corymbia maculata, commonly known as spotted gum, is a species of medium-sized to tall tree that is endemic to eastern Australia. It has smooth, mottled bark, lance-shaped to curved adult leaves, flower buds usually in groups of three, white flowers and urn-shaped or barrel-shaped fruit.
Corymbia polycarpa, also known as long-fruited bloodwood or small-flowered bloodwood, is a species of tree that is endemic to northern Australia. Indigenous Australians of different language groups have different names for the tree. The Nungali peoples know the tree as narrga or gunjid, the Mulluk-Mulluk know it as dawart, the Yangman know it as bodog, the Gurindji peoples as jadburru and the Wagiman as jagatjjin. It is a medium-sized tree with rough, tessellated bark on the trunk and branches, lance-shaped to curved adult leaves, flower buds in groups of seven or nine, white or cream-coloured flowers and barrel-shaped fruit.
Corymbia aparrerinja, commonly known as ghost gum, is a species of tree that is endemic to Central Australia. It has smooth bark, lance-shaped or curved adult leaves, flower buds in groups of three or seven, white flowers and cup-shaped to cylindrical fruit.
p-Menthane-3,8-diol, also known as para-menthane-3,8-diol, PMD, or menthoglycol, is an organic compound classified as a diol and a terpenoid. It is colorless. Its name reflects the hydrocarbon backbone, which is that of p-menthane. A total of eight stereoisomers are possible, based on the three stereocenters of the ring. Depending on the source, one or more may predominate.
Corymbia henryi, commonly known as large-leaved spotted gum, is a species of small to medium-sized tree that is endemic to north-eastern Australia. It has smooth, mottled bark, lance-shaped adult leaves, flower buds in groups of three, white or lemon yellow flowers and barrel-shaped to urn-shaped fruit.
Corymbia aspera, commonly known as rough-leaved ghost gum, rough leaf range gum, desert bloodwood, Brittle Range gum in Western Australia, or snappy gum in the Northern Territory is a species of tree that is endemic to northern Australia. It has smooth white bark, sometimes with a short stocking of rough bark near the base, a crown of sessile juvenile, heart-shaped or egg-shaped leaves, flower buds in groups of seven, creamy white flowers and cup-shaped, barrel-shaped or cylindrical fruit.
Corymbia dichromophloia, commonly known as small-fruited bloodwood, variably-barked bloodwood or gum-topped bloodwood, is a species of tree that is endemic to northern Australia. It has smooth white bark sometimes with flaky bark on the trunk, lance-shaped adult leaves, flower buds usually in groups of seven, creamy white flowers and urn-shaped fruit.
Corymbia erythrophloia, commonly known as red bloodwood, variable-barked bloodwood, red-barked bloodwood or gum-topped bloodwood, is a species of tree that is endemic to Queensland. It has rough bark on the trunk and branches, egg-shaped or lance-shaped adult leaves, flower buds in groups of seven, creamy white flowers and urn-shaped to spherical fruit.
Corymbia ferriticola, commonly known as Pilbara ghost gum, is a species of tree or a mallee that is endemic to Western Australia. It has smooth bark, lance-shaped adult leaves, flower buds in groups of seven, creamy white flowers and shortened spherical to cylindrical fruit.
Corymbia gilbertensis, commonly known as Gilbert River ghost gum or Gilbert River box, is a species of tree that is endemic to tropical far north Queensland. It has rough, tessellated bark on the lower part of the trunk, smooth bark above, a crown of juvenile, intermediate and adult leaves, flower buds mostly in groups of seven, creamy white flowers and cup-shaped to barrel-shaped fruit.
Corymbia grandifolia, commonly known as cabbage gum, large-leaved cabbage gum and paper-fruited bloodwood, is a species of tree that is endemic to northern Australia. It has smooth bark, egg-shaped to broadly elliptic to lance-shaped adult leaves, flowers buds in groups of three or seven, creamy white flowers and cup-shaped to cylindrical fruit.
Corymbia torelliana, commonly known as cadaghi or cadaga, is a species of tree that is endemic to north Queensland. It has smooth, greenish grey to white bark, rough at the base of older trees, egg-shaped, heart-shaped or lance-shaped adult leaves, flower buds in groups of three or seven, white flowers and urn-shaped or shortened spherical fruit.