Diuris

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Donkey orchids
Diuris 03 gnangarra.jpg
Diuris corymbosa
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Subtribe: Diuridinae
Genus: Diuris
Sm. [1]

Diuris, commonly known as donkey orchids, bee orchids, nanny goat orchids or pansy orchids, [2] is a genus of more than sixty species of flowering plants in the orchid family, Orchidaceae and is endemic to Australia, apart from one species endemic to Timor. The name "Diuris" refers to the hanging sepals but the common name "donkey orchid", derives from the ear-like petals common to all species. Many have mainly yellow flowers with darker markings and are thought to mimic nectar-producing flowers which open at the same time.

Contents

Description

Orchids in the genus Diuris are terrestrial, perennial, deciduous, sympodial herbs, usually with a few inconspicuous, fine roots and one or two tubers lacking a protective sheath. The stem is short, erect and unbranched with a leaf-like cataphyll at each node. There are between one and ten grass-like leaves at the base of the plant. [3] [4] [5] [6]

Labelled image Diuris (labelled).jpg
Labelled image

The inflorescence is a raceme with a few to many brightly coloured, resupinate flowers on a wiry stalk. The dorsal sepal is shorter but wider than two lateral sepals and forms a hood over the column. The long, narrow, lateral sepals hang like a pair of tails below the labellum. The petals are different from the sepals, having a narrow base with the main part widely expanded, in the form of donkey ears. As is usual in orchids, one petal is highly modified as the central labellum, differing markedly from the other petals and sepals. The labellum has three distinct parts with the central part folded and the lateral parts arranged on either side of the column, often spreading widely, sometimes with a scalloped or wavy edge. The column is short with narrow wings. Flowering time depends on the species but most species flower between September and November. One of the earliest to flower, D. brumalis flowers in June and D. emarginata sometimes flowers as late as January. The fruit which follows flowering is a thin-walled, dehiscent capsule containing up to 100 winged seeds. [3] [4] [5] [6]

Taxonomy and naming

The genus Diuris was first formally described in 1798 by James Edward Smith and the description was published in Transactions of the Linnean Society of London . Smith did not nominate a type species. [7] [8]

The common name "donkey orchid" refers to the ear-like petals. [3] The scientific name is derived from the Greek dis meaning 'double' and oura, 'tail', referring to the two narrow lateral sepals. [2]

Distribution and habitat

Donkey orchids occur in all Australian states, but not the Northern Territory with one species ( D. fryana ) found in Timor. In New South Wales, most species grow among grasses in sclerophyll forest. [6] In Western Australia, most grow in moist places such as coastal swamps or near granite outcrops. [3] Donkey orchids usually grow as individual plants or in loose colonies and most occur at low altitudes, although D. monticola grows at up to 1,800 m (6,000 ft). Some species flower more profusely after fire and D. purdiei will only flower following a summer fire. [4] In fire-prone areas, the tubers lie dormant in the soil and are not harmed by bushfires. [3]

Ecology

Donkey orchids are coloured like flowers that attract pollinating insects such as wasps, bees and flies but no Diuris produce nectar and very few have a scent. It is thought that Diuris species deceive insects by falsely advertising the presence of food and this hypothesis is supported by experiments on only one species, D. pardina . [4]

Species

The following is a list of Diuris species accepted by the Plants of the World Online as of September: [9]

Natural hybrids

Related Research Articles

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<i>Daviesia</i> Genus of plants

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<i>Genoplesium</i> Genus of orchids

Genoplesium commonly known as midge orchids, is a genus of about 50 species of flowering plants in the orchid family, Orchidaceae and is found in Australia, New Zealand and New Caledonia. Midge orchids are terrestrial herbs with a single leaf at the base of the plant. They are similar to orchids in the genus Prasophyllum in that plants without flowers have a hollow, onion-like leaf. The flowers are small but often scented and attractive to their insect pollinators. There is disagreement about which species belong to this genus and some taxonomists suggest that most belong in the genus Corunastylis.

Diuris fragrantissima, commonly called the fragrant doubletail or Sunshine diuris, is a species of orchid which is endemic to a small area to the west of Melbourne. It has two linear leaves at its base and up to twelve white flowers with mauve or pale purple markings with unusually long lateral sepals. Only about thirty plants survive in grassland near Sunshine.

<i>Diuris tricolor</i> Species of orchid

Diuris tricolor, commonly known as the long-tailed donkey orchid or pine donkey orchid, is a species of orchid that is endemic to eastern Australia. It has up to three grass-like leaves and up to six orange-coloured to yellow flowers with white and purplish tints. The lateral sepals are unusually long.

References

  1. "Diuris". Australian Plant Census. Retrieved 17 April 2023.
  2. 1 2 Brown, Andrew; Dixon, Kingsley; French, Christopher; Brockman, Garry (2013). Field guide to the orchids of Western Australia : the definitive guide to the native orchids of Western Australia. Simon Nevill Publications. p. 200. ISBN   9780980348149.
  3. 1 2 3 4 5 Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. pp. 456–497. ISBN   9780646562322.
  4. 1 2 3 4 Pridgeon, Alec M.; Cribb, Phillip J.; Chase, Mark W.; Rasmussen, Finn, eds. (2001). Genera Orchidacearum, Volume 2, Orchidoideae (part 1). Oxford, England: Oxford University Press. pp. 126–131. ISBN   0198507100.
  5. 1 2 "Diuris". FloraBase . Western Australian Government Department of Biodiversity, Conservation and Attractions.
  6. 1 2 3 Jones, David L. "Genus Diuris". Royal Botanic Garden Sydney: plantnet. Retrieved 21 July 2016.
  7. "Diuris". APNI. Retrieved 21 July 2016.
  8. Smith, James Edward (1798). "The Characters of Twenty New Genera of Plants". Transactions of the Linnean Society of London. 4: 222. Retrieved 21 July 2016.
  9. "Diuris". Plants of the World Online. Retrieved 19 September 2023.