Dipodium

Dipodium, commonly known as hyacinth orchids,[3] is a genus of about forty species of orchids native to tropical, subtropical and temperate regions of south-east Asia, New Guinea, the Pacific Islands and Australia. It includes both terrestrial and climbing species, some with leaves and some leafless, but all with large, often colourful flowers on tall flowering stems. It is the only genus of its alliance, Dipodium.

For another orchid called "hyacinth orchid", see Bletilla striata.

Hyacinth orchids
Dipodium punctatum
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Subtribe: Eulophiinae
Genus: Dipodium
R.Br.[1]
Type species
Dipodium punctatum[1]
Species

See text

Synonyms[2]

Description

Orchids in the genus Dipodium are perennial, terrestrial herbs or climbers/epiphytes. Many species, particularly in eastern Australia are leafless mycoheterotrophs. Others have medium-sized to very large leaves that are parallel-veined and have entire margins. The flowers are arranged in a raceme with very few or up to fifty large, often colourful flowers. These may be fragrant or odourless, are white, pink, purple, yellow or green, often with spots or blotches. The sepals and petals are free from and similar to each other. The labellum projects forwards and has three lobes with a central band of colourful hairs. Each flower has two pollinia that are supported on two stipes. Dehiscent capsules, produced after flowering, hold the seed which is released when the capsule splits longitudinally along six seams. Between 30 and 500 seeds are produced per capsule.[3][4][5][6]

Taxonomy

The genus was formally described in 1810 by Scottish botanist Robert Brown in Prodromus Florae Novae Hollandiae et Insulae Van Diemen.[1][7] The name Dipodium is derived the Greek words di (two) and podia (little feet), a reference to the two stipes supporting the pollinia.[8]

Two flowering scapes of a leafless species in south-eastern Australia

Distribution and habitat

Hyacinth orchids are found in Malaysia, the Philippines, Indonesia, the Solomon Islands, the New Hebrides, New Caledonia, New Guinea and Australia where eleven species are endemic. They occur in a range of habitats from coastal lowlands to ranges and tablelands.[3][9]

Ecology

It is thought that the flowers attract native bees and wasps through floral mimicry.[10]

Uses

An infusion of the leaves of Dipodium pandanum is traditionally drunk in Bouganville to help relieve respiratory infections.[11]

Use in horticulture

Leafless hyacinth orchids are impossible to grow in cultivation but D. pandanum is easy to grow in warm climates.[3]:272

Species

The following is a list of described species in the genus Dipodium, recognised by the World Checklist of Selected Plant Families[2] apart from Dipodium punctatum which is recognised as a species in Australia (rather than as a synonym of Dipodium squamatum).[1][12]

Undescribed species
  • Dipodium sp. Basalt Woodland (M.D. Barrett 198) - northern Kimberley, Western Australia.[13]
  • Dipodium sp. Sandstone (R.L. Barrett & K.W. Dixon 1642) - northern Kimberley,[14]

References
  1. "Dipodium". APNI. Retrieved 12 July 2018.
  2. "Dipodium". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew. Retrieved 12 July 2018.
  3. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 270. ISBN 1877069124.
  4. "Dipodium R.Br". FloraBase. Western Australian Government Department of Parks and Wildlife.
  5. Weston, P.H. "Genus Dipodium". PlantNET - New South Wales Flora Online. Royal Botanic Gardens & Domain Trust, Sydney Australia. Retrieved 7 February 2014.
  6. Jeanes, Jeff. "Dipodium". Royal Botanic Gardens Victoria. Retrieved 12 July 2018.
  7. Brown, Robert (1810). Prodromus Florae Novae Hollandiae et Insulae Van Diemen. London. pp. 330–331. Retrieved 12 July 2018.
  8. Clements, Mark A (2013). The Allure of Orchids. National Library Australia. pp. 48–51. ISBN 978-0-642-27807-4.
  9. Jones, David L. (1991). "New taxa of Australian Orchidaceae". Australian Orchid Research. 2: 48.
  10. Jessup, Scott. "Action statement - yellow hyacinth orchid Dipodium hamiltonianum" (PDF). The State of Victoria, Department of Sustainability and Environment. Retrieved 12 July 2018.
  11. Lawler, L.J.; Slaytor, M. (1969). "The distribution of alkaloids in orchids from the territory of Papua and New Guinea". Proceedings of the Linnean Society of New South Wales. 94: 240. Retrieved 8 February 2014.
  12. "Dipodium punctatum". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew. Retrieved 12 July 2018.
  13. "Dipodium sp. Basalt Woodland (M.D. Barrett 198)". FloraBase. Western Australian Government Department of Parks and Wildlife.
  14. "Dipodium sp. Sandstone (R.L. Barrett & K.W. Dixon 1642)". FloraBase. Western Australian Government Department of Parks and Wildlife.
  • Media related to Dipodium at Wikimedia Commons
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