''Eucalyptus risdonii'', commonly known as the Risdon peppermint, is a species of small tree that is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Meehan Range The Meehan Range ( ) is a prominent geographic feature in southeastern Tasmania, consisting of steep hills and ridges running parallel to the River Derwent (Tasmania), River Derwent on the eastern shore of Hobart. Situated primarily in the C ...

within Greater Hobart and

Mangalore Mangaluru (), formerly called Mangalore ( ), is a major industrial port city in the Indian state of Karnataka and on the west coast of India. It is located between the Laccadive Sea and the Western Ghats about west of Bengaluru, the st ...

Tasmania, Australia Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

. It has smooth bark, a

crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, parti ...

composed mostly of

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

glaucous ''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), ...

, egg-shaped juvenile leaves arranged in opposite pairs. The flower buds are arranged in groups of between nine and fifteen and the fruit are cup-shaped, conical or hemispherical.

Description

''Eucalyptus risdonii'' is a tree that typically grows to a height of and forms a

lignotuber A lignotuber is a woody swelling of the root crown possessed by some plants as a protection against destruction of the plant stem, such as by fire. Other woody plants may develop basal burls as a similar survival strategy, often as a respons ...

. The bark is smooth, grey, yellow, white or cream-coloured. Young plants and

coppice Coppicing is the traditional method in woodland management of cutting down a tree to a tree stump, stump, which in many species encourages new Shoot (botany), shoots to grow from the stump or roots, thus ultimately regrowing the tree. A forest ...

regrowth have glaucous, sessile, egg-shaped leaves arranged in opposite pairs with their bases joined, long and wide. The crown is composed mostly of juvenile leaves. Adult leaves, when formed, are arranged alternately, dull green, lance-shaped, up to long and wide. The flower buds are arranged in leaf

axil A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, fl ...

s, on an unbranched peduncle long, the individual buds on

pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branch ...

long. Mature buds are oval to club-shaped, long and wide with a rounded to flattened operculum. Flowering occurs from November to January and the flowers are white. The fruit is a woody cup-shaped, conical or hemispherical capsule long and wide with the valves below rim level.

Taxonomy and naming

''Eucalyptus risdonii'' was first formally described in 1847 by

Joseph Dalton Hooker Sir Joseph Dalton Hooker (30 June 1817 – 10 December 1911) was a British botanist and explorer in the 19th century. He was a founder of geographical botany and Charles Darwin's closest friend. For 20 years he served as director of the Ro ...

in the ''London Journal of Botany''. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

(''risdonii'') refers to the locality Risdon, where the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

specimen was found.

Distribution and habitat

The Risdon peppermint is only known from the dry slopes on the eastern side of the River Derwent within the Meehan Range near Risdon, Grasstree Hill and

. It grows in low, open forest on sunny, north-west facing ridges. This species is reported to be a juvenilised form of its

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

, '' E. tenuiramis''.

Conservation status

This species is classed as "rare" under the Tasmanian Government ''

Threatened Species Protection Act 1995 The ''Threatened Species Protection Act 1995'' (TSP Act), is an act of the Parliament of Tasmania that provides the statute relating to conservation of flora and fauna. Its long title is An Act to provide for the protection and management of ...

''.

References

External links

{{DEFAULTSORT:Eucalyptus Risdonii Endemic flora of Tasmania Myrtales of Australia Trees of Australia Plants described in 1847 Taxa named by Joseph Dalton Hooker