Urn tree facts for kids
Quick facts for kids Urn gum |
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| Sketches of E. urnigera from A critical revision of the genus Eucalyptus (1903-33). | |
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Eucalyptus
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| Species: |
urnigera
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The Eucalyptus urnigera, also known as the urn tree, is a type of small to medium-sized tree. It is found only in Tasmania, which means it is endemic there. This tree has smooth bark, leaves shaped like spears or ovals, and its flower buds grow in groups of three. It produces white flowers and fruit shaped like an urn.
Contents
What Does the Urn Gum Look Like?
The Eucalyptus urnigera is an evergreen tree. This means it keeps its leaves all year round. It usually grows to be about 5 to 15 meters (16 to 49 feet) tall. Some very tall ones have been seen, reaching up to 45 meters (148 feet) in places that are protected from wind. The tree can spread out to about 10 meters (33 feet) wide.
This tree has a special woody swelling at its base called a lignotuber. This helps it regrow if the top part is damaged. In windy areas, the tree often looks twisted. But in sheltered, lower places, it grows tall and straight.
The bark of the urn gum is smooth and has patches of grey, orange-tan, and olive green over a creamy color. It peels off in flakes. The younger branches often have a whitish, waxy coating, which is called being glaucous.
Leaves and Flowers
Young plants and new shoots have leaves that are directly attached to the stem, without a stalk. This is called being sessile. These leaves are heart-shaped to round, about 12 to 28 mm long and 13 to 28 mm wide. They grow in opposite pairs and wrap around the stem. Their edges are slightly notched or wavy. These young leaves can be dark green in sheltered spots or glaucous (waxy) in exposed areas.
Adult leaves grow one after another along the stem. They are the same shade of green on both sides. They can be spear-shaped, broadly spear-shaped, or oval. They are about 35 to 90 mm long and 10 to 28 mm wide. They narrow down to a leaf stalk, called a petiole, which is 7 to 30 mm long.
The flower buds grow in groups of three in the axils (the angle between a leaf and the stem). They hang downwards on a stalk called a peduncle, which is 5 to 25 mm long. Each individual bud has its own small stalk, called a pedicel, which is 1 to 13 mm long.
Mature buds are shaped like a cylinder or an urn and are often glaucous. They are about 10 to 13 mm long and 5 to 7 mm wide. They have a flattened, slightly beaked cap, called an operculum, which is wider than the base of the flower (the floral cup) where they join.
The urn gum flowers for most of the year, but it blooms most from April to July. Its flowers are white. After flowering, the fruit develops into a woody, urn-shaped capsule. These capsules are 9 to 15 mm long and 6 to 11 mm wide, and the parts that open to release seeds are below the rim.
Why Do Leaves Change Color?
Most Eucalyptus urnigera trees look quite similar, but there's one interesting difference: their leaf color. The amount of waxiness (glaucicity) on the leaves changes depending on where the tree grows.
Trees at lower altitudes (around 560–670 meters or 1,837–2,198 feet) in shady forests have green leaves. But trees at higher altitudes (around 950–1050 meters or 3,117–3,445 feet) in more exposed areas have glaucous (waxy) leaves. You can see this change clearly on a walking path on Mount Wellington. The leaves change from green to waxy within just 200 meters (656 feet) of altitude.
Scientists believe that green leaves are better at photosynthesizing (making food from sunlight) in low light conditions, like in a dense forest. However, at higher altitudes, there is more direct sunlight. The waxy coating on glaucous leaves helps reflect sunlight, especially infrared light. This coating also helps protect the tree from frost.
How the Urn Gum Got Its Name
The Eucalyptus urnigera was first officially described in 1847 by an English botanist named Joseph Hooker. He wrote about it in a journal called London Journal of Botany. The specimens (samples) of the tree were collected by Ronald Campbell Gunn from Mount Wellington and Lake Echo in Tasmania.
The second part of the tree's scientific name, urnigera, comes from two Latin words: urna, meaning "urn," and gero, meaning "to bear." This name was chosen because of the tree's unique urn-shaped flower buds and seed capsules.
Where Does the Urn Gum Grow?
The Eucalyptus urnigera is a type of eucalypt that grows only in the alpine (mountain) areas of Tasmania. It is found at altitudes from about 600 to 1000 meters (1,969 to 3,281 feet). It prefers moist but well-drained slopes and rocky areas made of a type of rock called dolerite.
This tree is found in the mountains of southeastern Tasmania, including the Mount Wellington range and Mount Field. You can also find isolated groups of them further south near Southport, about 100 kilometers (62 miles) south of Hobart. They also grow north to Alma Tier near Interlaken and Mount Seymour east of Oatlands in central Tasmania. There's also a small group on the eastern side of Maria Island.
The urn gum usually grows below where the E. coccifera (snow gum) grows. It also grows above the mixed and wet sclerophyll forests found on lower slopes. However, it can sometimes be found growing within both of these other types of vegetation.
Who Helps the Urn Gum Reproduce?
The flowers of the Eucalyptus urnigera are pollinated by birds. This means birds help carry pollen from one flower to another, which allows the tree to make seeds. Some of the birds that help pollinate the urn gum include the yellow-throated honeyeater (Lichenostomus flavicollis), the black-headed honeyeater (Melithreptus affinis), and the strong-billed honeyeater (Melithreptus validirostris).
Why Is the Urn Gum Useful?
The Eucalyptus urnigera is not used for timber (wood) in Tasmania. However, it is highly valued as a special tree in gardens in cooler parts of the United States and the British Isles. Some nurseries even think it's better than E.gunni, another type of eucalypt often grown in the UK.
Its colorful bark and interesting leaves make it a great choice for decorating gardens. Because it has a lignotuber, it can be coppiced (cut back to the base to regrow). This makes it a good option for producing firewood in places like the United Kingdom.
