''Richea milliganii'', commonly known as the nodding candle heath or Milligan's candle heath, is a common species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

in the family

Ericaceae The Ericaceae () are a Family (biology), family of flowering plants, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with about 4,250 known species spread acros ...

. It is endemic to

Tasmania 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 ...

. Compared to other ''Richea'' species, ''R. milliganii'' can be identified by its distinctive pale-yellow drooping flower heads, hence the common name.

Description

''Richea milliganii'' is an erect shrub of in height with straight, spreading, somewhat soft leaves. Its leaves are

lanceolate The following terms are used to describe leaf plant morphology, morphology in the description and taxonomy (biology), taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade ...

in shape and can reach up to in length. Its inflorescences consist of 8-15 pale yellow flowers in distinctive drooping terminal heads, and each flower has five stamens.

Habitat and distribution

''Richea milliganii'' is a common shrub found across western and southern Tasmania from lower altitudes up to mountainous subalpine areas of c. . It may be found as far north as

Mount Read Mount Read is a mountain located in the West Coast region of Tasmania, Australia, and is at the north west edge of the West Coast Range. With an elevation of above sea level, Mount Read has had as colourful a history, similar to that of Mou ...

. It favours peaty, low-nutrient soils in

montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

areas or open heathland. At lower altitudes, it is primarily found in woodlands or at the margins of buttongrass plains.

Taxonomy

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 ...

was the first European to describe this plant in his publication, '' The Botany of the Antarctic Voyage of H.M. Discovery Ships Erebus and Terror'', which was first published in 1844. In this publication, Hooke named the species ''Pilitis milliganii''. The species was moved to the genus '' Cystanthe'' by

Ferdinand von Mueller Baron Sir Ferdinand Jacob Heinrich von Mueller, (; 30 June 1825 – 10 October 1896) was a German-Australian physician, geographer, and most notably, a botanist. He was appointed government botanist for the then colony of Victoria, Australia ...

in 1858, who then reclassified it again in 1867, this time as ''R. milliganii.''

Diversity and endemism

This species is one of the nine Tasmanian endemic species belonging to the genus

Richea ''Richea'' is a genus of 11 species of flowering plants in the family Ericaceae. Nine of the species are endemic to Tasmania and the other two are endemic to the south-east of the Australian mainland. Species include: *'' Richea acerosa'' (Lin ...

, with the remaining two species in the genus being endemic to south-eastern mainland Australia. There are two main theories as to why this genus is not found far outside of Tasmania. The first is that these species are

paleoendemic Paleoendemism along with neoendemism is a possible subcategory of endemism. Paleoendemism refers to species that were formerly widespread but are now restricted to a smaller area. Neoendemism refers to species that have recently arisen, such as th ...

, originating from the supercontinent Gondwana, and are relics of speciation that occurred before Gondwana's fragmentation. This supports the idea that favourable conditions for these species have persisted in Tasmania to a greater extent than on mainland Australia. The second theory is that these species diverged after the breakup of Gondwana and then underwent speciation, mostly adapting towards Tasmanian environments, while a minority of species dispersed to or continued to survive in mainland Australian habitats.

Threats and conservation

While much of ''R. milliganii'''s habitat is protected in Tasmania, this habitat is primarily alpine heathland, which may experience significant environmental changes in coming years. These change could include temperature changes and wildfires, which can result in landscape disturbance and the potential loss of some species. Alpine heathlands contain some of the highest rates of endemism in Tasmania, with the genus ''Richea'' being a good example of this. Changes in these habitats may have significant impacts on local endemics such as ''R. milliganii'', and as such should be monitored closely.

References

{{Taxonbar, from=Q17245914 milliganii Flora of Tasmania Plants described in 1844