''Dipodium hamiltonianum'', commonly known as yellow hyacinth-orchid, is a leafless

mycoheterotroph Myco-heterotrophy (from Greek μύκης , "fungus", ἕτερος ', "another", "different" and τροφή ', "nutrition") is a symbiotic relationship between certain kinds of plants and fungi, in which the plant gets all or part of its food fro ...

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

that is

endemic Endemism is the state of a species being found 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 found elsew ...

to eastern Australia. It has up to twenty five greenish flowers with dark red spots on a tall flowering stem.

Description

For most of the year, ''D. hamiltonianum'' plants are dormant and have no above-ground presence. Below the ground lie fleshy roots. Flower spikes between 40 and 80 cm in height appear between November and March in the species' native range. These

racemose A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

inflorescences have 3 to 25 yellow or greenish-yellow fleshy flowers with red to purple spots. The three-lobed forward-projecting labellum is white with purple markings and has a tuft of white hairs. Tubers usually produce only a single flower spike. Flower spikes from an individual plant may appear as infrequently as once in a five-year period.

Taxonomy

The species was formally described by Queensland Colonial Botanist

Frederick Manson Bailey Frederick Manson Bailey (8 March 1827 – 25 June 1915) was a botanist active in Australia, who made valuable contributions to the characterisation of the flora of Queensland. He was known by his middle name, Manson. Early life Bailey was bo ...

in 1881 based on plant material collected from

Stradbroke Island Stradbroke Island, also known as Minjerribah, was a large sand island that formed much of the eastern side of Moreton Bay near Brisbane, Queensland until the late 19th century. Today the island is split into two islands: North Stradbroke Islan ...

and

Peel Island Peel Island (Indigenous, Janday: ''Teerk Roo Ra'', also and more phonetically spelled 'Jercuruba' or 'Jercroobai' ) is a small heritage-listed island located in Moreton Bay, east of Brisbane, in South East Queensland, Australia. The island i ...

near Brisbane in Queensland. In 1913, Bailey demoted the species, treating it as a subspecies of ''

Dipodium punctatum ''Dipodium punctatum'', commonly known as the blotched hyacinth-orchid, is a leafless orchid that is a native to eastern and south-eastern continental Australia. In summer it produces a tall flowering stem with up to sixty pale to bright pink fl ...

''. In 1944, botanist and orchid specialist

Herman Rupp Herman Montague Rucker Rupp (27 December 1872 – 2 September 1956) was an Australian clergyman and botanist who specialised in orchids. He was known throughout his life as Montague Rupp (pronounced "Rupe") and in later life as the "Orchid Man". R ...

reinstated the species. It is named for James Hamilton, superintendent of the Benevolent Asylum in

Dunwich Dunwich is a village and civil parish in Suffolk, England. It is in the Suffolk Coast and Heaths AONB around north-east of London, south of Southwold and north of Leiston, on the North Sea coast. In the Anglo-Saxon period, Dunwich was t ...

on Stradbroke Island who collected specimens for Bailey.

Distribution and habitat

The species occurs from

central Queensland Central Queensland is an ambiguous geographical division of Queensland ( a state in Australia) that centres on the eastern coast, around the Tropic of Capricorn. Its major regional centre is Rockhampton. The region extends from the Capricorn Coas ...

southwards through

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

and the

Australian Capital Territory The Australian Capital Territory (commonly abbreviated as ACT), known as the Federal Capital Territory (FCT) until 1938, is a landlocked federal territory of Australia containing the national capital Canberra and some surrounding townships. ...

to eastern

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

. Its altitudinal range is sea level to 800 metres AHD

Queensland

In Queensland it occurs southwards from the

Theodore Theodore may refer to: Places * Theodore, Alabama, United States * Theodore, Australian Capital Territory * Theodore, Queensland, a town in the Shire of Banana, Australia * Theodore, Saskatchewan, Canada * Theodore Reservoir, a lake in Sask ...

region. In tropical areas the habitat is recorded as grassy streamside areas, while in coastal areas they are found in scrub and heath. At

Noosa Heads Noosa Heads is a coastal town and suburb in the Shire of Noosa, Queensland, Australia. In the , the suburb of Noosa Heads had a population of 4,484 people. It is a popular holiday destination. Geography The suburb is bounded to the west by We ...

it has been observed in

wallum Wallum, or wallum country, is an Australian ecosystem of coastal south-east Queensland, extending into north-eastern New South Wales. It is characterised by flora-rich shrubland and heathland on deep, nutrient-poor, acidic, sandy soils, and re ...

woodland and dry heathland.

New South Wales

In New South Wales the species is recorded on dry western slopes on acidic sandy soils, as far west as the

Parkes Parkes may refer to: * Sir Henry Parkes (1815–1896), Australian politician, one of the earliest and most prominent advocates for Australian federation Named for Henry Parkes * Parkes, New South Wales, a regional town * Parkes Observatory, a radi ...

district. It is found on sandy soils at the southern end of Seven Mile Beach National Park on the south coast. It also recorded in the

Victoria

Seven populations have been recorded in low, open forest in north-eastern Victoria, usually among granite boulders. Four of these are in the

Beechworth Beechworth is a well-preserved historical town located in the north-east of Victoria, Australia, famous for its major growth during the gold rush days of the mid-1850s. At the , Beechworth had a population of 3,859. Beechworth's many histor ...

area, one in

Burrowa-Pine Mountain National Park The Burrowa-Pine Mountain National Park is a national park in the Hume region of Victoria, Australia. The national park is situated approximately northeast of Melbourne and east of Albury-Wodonga. The Pine Mountain, one of the largest monol ...

, one in Chiltern Regional Park and another on private land near Chesney Vale. Associated tree species in the Beechworth area include red stringybark (''

Eucalyptus macrorhyncha ''Eucalyptus macrorhyncha'', commonly known as the red stringybark, is a species of medium-sized tree that is endemic to eastern Australia. It has rough, stringy, grey to brown bark, lance-shaped adult leaves, flower buds in groups of between se ...

''), red box (''

Eucalyptus polyanthemos ''Eucalyptus polyanthemos'', commonly known as red box, is a species of small to medium-sized tree, that is native to eastern Australia but has been introduced into other countries. It has fibrous bark on the trunk and larger branches, smooth gr ...

''), Blakely's Red Gum (''

Eucalyptus blakelyi ''Eucalyptus blakelyi'', known as Blakely's red gum, is a tree endemic to eastern Australia. It has smooth bark on its trunk and branches, dull bluish green, lance-shaped adult leaves, flower buds usually in groups of seven, white flowers and cu ...

'') and black cypress-pine (''

Callitris endlicheri ''Callitris endlicheri'', commonly known as the black cypress pine, is a species of conifer in the family Cupressaceae. It is found only in Australia, occurring in Queensland, New South Wales, the Australian Capital Territory, and Victoria. Des ...

''). Associated shrub species at Chiltern and Chesney Vale include daphne heath ('' Brachyloma daphnoides''), hairy hop bush (''

Dodonaea boroniifolia ''Dodonaea'' is a genus of about 70 species of flowering plants, often known as hop-bushes, in the soapberry family, Sapindaceae. It has a cosmopolitan distribution in tropical, subtropical and warm temperate regions of Africa, the Americas, so ...

''), cats's claws ('' Grevillea alpina''), erect guinea-flower ('' Hibbertia riparia''), and flat-leaf bush-pea ('' Pultenaea platyphylla''). A further two populations are located near Wulgulmerang in East Gippsland, where white box (''

Eucalyptus albens ''Eucalyptus albens'', known as the white box, is a common tree of the western slopes and plains of New South Wales and adjacent areas in Queensland and Victoria. It has rough, fibrous bark on the base of its trunk and smooth, white bark above. ...

'') is the dominant species. The flowering period in Victoria is December to January. The species generally occurs on dry, well-drained north-facing slopes on granitic soils.

Ecology

It is thought that the flowers may be pollinated by small native bees or wasps. Grazing wallabies (often black wallabies (''

Wallabia bicolor The swamp wallaby (''Wallabia bicolor'') is a small macropod marsupial of eastern Australia. This wallaby is also commonly known as the black wallaby, with other names including black-tailed wallaby, fern wallaby, black pademelon, stinker (in Qu ...

'') in Victoria) may incidentally cut off flower spikes but do not consume them.

Conservation

Research has been undertaken to investigate the ecological requirements of the species to assist with both its in-situ conservation as well as conservation through cultivation. The principal fungal

endophyte An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; h ...

s were found to be species of two genera within the family

Russulaceae The Russulaceae are a diverse family of fungi in the order Russulales, with roughly 1,900 known species and a worldwide distribution. They comprise the brittlegills and the milk-caps, well-known mushroom-forming fungi that include some edible ...

, '' Gymnomyces'' and ''

Russula ''Russula'' is a very large genus composed of around 750 worldwide species of ectomycorrhizal mushrooms. They are typically common, fairly large, and brightly colored – making them one of the most recognizable genera among mycologists and mushr ...

''. Ectomycorrhizal species in this family are commonly associated with eucalypts in Australia, however the study did not identify a preferred tree host species. The species is listed as "threatened" in

under the

Flora and Fauna Guarantee Act 1988 The ''Flora and Fauna Guarantee Act 1988'', also known as the ''FFG Act'', is an act of the Victorian Government designed to protect species, genetic material and habitats, to prevent extinction and allow maximum genetic diversity within the Au ...

and "Vulnerable in Victoria" on the Department of Sustainability and Environment's ''Advisory List of Rare Or Threatened Plants In Victoria''. The population of the species in Victoria in 1997 was 105 plants, recorded in 9 locations.

Cultivation

To date, the orchid has not been brought in to cultivation or successfully transplanted due to the inability to replicate its association with mycorrhizal fungi in a horticultural context.

References

{{Taxonbar, from=Q14942849 hamiltonianum Orchids of the Australian Capital Territory Orchids of New South Wales Orchids of Queensland Orchids of Victoria (state) Endemic orchids of Australia