Drakaea

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Hammer orchid
Drakaea glyptodon.jpg
Flower of Drakaea glyptodon
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: Drakaeinae
Genus: Drakaea
Lindl. [1]

Drakaea is a genus of 10 species in the plant family Orchidaceae commonly known as hammer orchids. All ten species occur only in the south-west of Western Australia. Hammer orchids are characterised by an insectoid labellum that is attached to a narrow, hinged stem, which holds it aloft. The stem can hinge only backwards, where the broadly winged column carries the pollen and stigma. Each species of hammer orchid is pollinated by a specific species of thynnid wasp. Thynnid wasps are unusual in that the female is flightless and mating occurs when the male carries a female away to a source of food. The labellum of the orchid resembles a female thynnid wasp in shape, colour and scent. Insect pollination involving sexual attraction is common in orchids but the interaction between the male thynnid wasp and the hammer orchid is unique in that it involves the insect trying to fly away with a part of the flower.

Contents

Description

Hammer orchids have a single thumbnail-sized, flat, heart-shaped, fleshy, ground-hugging leaf and a long, thin, wiry stem. The stem bears a leaf-like bract below half way and a single flower at its summit. The flower is highly modified in that the labellum resembles a female thynnid wasp in shape and colour and which produces a scent that mimicks a pheromone produced by the female. There is a single (male) stamen bearing two pollinia close to the single (female) stigma. After fertilisation, the ovary develops into a non-fleshy capsule containing up to 500 seeds. [2]

D. glyptodon labelled image Drakaea labelled.jpg
D. glyptodon labelled image

Pollination mechanism

Many orchid species have structures, or produce scents that mimic female insects and are attractive to males. Hammer orchids are unique in that they are pollinated by a species of male thynnid wasp (Superfamily Vespoidea, Family Thynnidae). Thynnid wasps are unique in that the females are flightless. When male wasps emerge from the ground, they search for females. When the flightless female wasps emerge, they climb a blade of grass, rub their legs together, release a pheromone and wait for males. When a male detects the pheromone, it flies in a zig-zag pattern upwind until the female is located. The male grasps the female and flies away with her to a food source. Copulation occurs in flight and the male feeds his mate through his abdomen. She is then left to return to the ground, lay her eggs in beetle larvae and die. [3]

The orchid produces a chemical that mimics the pheromone produced by the female wasp and is strongly attractive to male thynnid wasps. (One researcher had male wasps follow his car, fly through the open windows and locate orchids on the floor of the car.) When a male is attracted by the pheromone-like scent released by the orchid and by its shape, it tries to fly away with the labellum, making the stem holding it move backwards. This in turn brings the male wasp's thorax in contact with the sticky pollen packet. The male wasp tires of trying to remove the labellum and flies off. In order for the hammer orchid to be successfully pollinated, the male wasp must visit another individual orchid, where it goes through the same procedure. This time the pollen is deposited on the stigma, and so that plant has been pollinated. [4] [5] [6]

Usually each species of orchid is pollinated by a specific species of wasp, but there are exceptions. One hammer orchid species shares a pollinator with other kinds of orchid [7] and one population of Drakaea concolor attracts a rare and poorly known wasp whilst another also attracts a second, far more common species. [5]

Drakaea thynniphila Drakaea thynniphila.jpg
Drakaea thynniphila

Taxonomy and naming

The taxonomy of many orchid genera is debated and there have been many changes to genera such as Caladenia . [8] Hammer orchids, however are unique, are easily distinguished from other genera and there have been few changes to the limits of the genus since they were first described. However, there has been confusion and disagreement about classification within the genus. The latest review was carried out by Stephen Hopper and Andrew Brown in 2007. [9]

The first species of hammer orchid to be formally described was Drakaea elastica . John Lindley described that species in 1840 in A Sketch of the Vegetation of the Swan River Colony . [10] [11] The common name (hammer orchid) refers to the shape of the labellum and the way it moves when the flower is being pollinated by a male insect. [12] The genus name (Drakaea) honours Sarah ("Ducky") Drake, [9] a botanical artist who drew orchids and other plants to assist taxonomists in England in the 19th century. [13]

Distribution and habitat

The ten species of Drakaea are all found within the south-west botanical province of Western Australia, between the Esperance and Geraldton districts. They usually grow in sandy soil in loose, scattered colonies. [2] [14]

Conservation

Five species of Drakaea have been classified by the Western Australian government Department of Parks and Wildlife as "Threatened", meaning that they are likely to become extinct or are in need of special protection and one is listed as "Priority One" meaning that it is known from one or a few locations [15] which are potentially at risk.

A study [16] has shown that the rarity of many species of Drakaea is most likely to be due to habitat loss, the rarity of the specific pollinator or a narrow habitat requirement than the absence of the required mycorrhizal fungus or because of poor rates of germination.

List of species

The following is a listed of species accepted by the World Checklist of Selected Plant Families as at July 2019:

Related Research Articles

<i>Caladenia</i> Genus of orchids

Caladenia, commonly known as spider orchids, is a genus of 350 species of plants in the orchid family, Orchidaceae. Spider orchids are terrestrial herbs with a single hairy leaf and a hairy stem. The labellum is fringed or toothed in most species and there are small projections called calli on the labellum. The flowers have adaptations to attract particular species of insects for pollination. The genus is divided into three groups on the basis of flower shape, broadly, spider orchids, zebra orchids and cowslip orchids, although other common names are often used. Although they occur in other countries, most are Australian and 136 species occur in Western Australia, making it the most species-rich orchid genus in that state.

<i>Chiloglottis</i> Genus of orchids

Chiloglottis, commonly known as wasp orchids, ant orchids or bird orchids, is a genus of about 25 species of flowering plants in the orchid family, Orchidaceae and is found in eastern Australia and New Zealand. Wasp orchids are terrestrial herbs which grow in colonies of genetically identical plants. They usually have two leaves at the base of the plant and a single resupinate ("upside-down") flower. The labellum is more or less diamond-shaped and has calli resembling the body of a wingless female wasp.

<i>Arthrochilus</i> Genus of flowering plants

Arthrochilus, commonly called elbow orchids, is a genus of about fifteen species of flowering plants from the orchid family (Orchidaceae) and is found in Australia and New Guinea. The flowers are pollinated by male thynnid wasps which attempt to mate with the flower and are held in place by hooks while the pollinium is transferred between insect and flower.

<i>Cryptostylis</i> Species of orchid

Cryptostylis, commonly known as tongue orchids, is a genus of flowering plants from the orchid family. Tongue orchids are terrestrial herbs with one to a few stalked leaves at the base of the flowering stem, or leafless. One to a few dull coloured flowers are borne on an erect flowering stem. The most conspicuous part of the flower is the labellum, compared to the much reduced sepals and petals. At least some species are pollinated by wasps when they attempt to mate with the flower. There are about twenty five species found in South Asia, Southeast Asia and the South Pacific.

<i>Spiculaea</i> Genus of orchids

Spiculaea is a genus of plants defined by a single species, Spiculaea ciliata, commonly known as elbow orchid, and allied to the family Orchidaceae. Endemic to the south-west of Western Australia, the species is unusual in a number of respects; it grows in shallow soil on granite rock outcrops, grows and flowers in the hottest months of the year and has a unique method of using thynnid wasps as pollinators.

<i>Caleana</i> Genus of flowering plants

Caleana, commonly known as duck orchids, is a genus of flowering plants in the orchid family, Orchidaceae that is found in Australia and New Zealand. The Australian species are found in all states but have not been recorded in the Northern Territory. Duck orchids have a single leaf and one or a few, dull-coloured, inconspicuous flowers. Most species are found in Western Australia but one species occurs in eastern Australia and one occurs in eastern Australia and New Zealand. Orchids in this genus as well as the hammer orchids (Drakaea) are pollinated by male thynnid wasps.

<span class="mw-page-title-main">Diurideae</span> Tribe of orchids

Diurideae is a tribe of orchid in the subfamily Orchidoideae. It contains about 40 accepted genera. As of April 2018, its division into subtribes remained unclear.

Drakaea concolor, commonly known as the kneeling hammer orchid, is a species of orchid endemic to the south–west of Western Australia. The species is only known from a few areas in the far west of the state and has been declared "vulnerable" by the Australian Government and "threatened" by the Government of Western Australia.

Drakaea confluens, commonly known as late hammer orchid, is a species of orchid endemic to the south–west of Western Australia. It is similar to other hammer orchids in that it is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a specific species of flightless female thynnid wasp. The species was discovered and collected in 1930 but was not formally described until 2007. It is only known from three areas in the south of the state and has been declared "endangered" by the Australian government and "threatened" by the Government of Western Australia.

<i>Drakaea elastica</i> Species of orchid endemic to Western Australia

Drakaea elastica, commonly known as glossy-leaved hammer orchid or praying virgin is a species of orchid endemic to the south–west of Western Australia. It is similar to other hammer orchids in that it is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. The glossy-leaved hammer orchid was the first in the genus to be described. The species is only known from the far south-west of the state and has been declared "endangered" by both the Australian government and the government of Western Australia.

<i>Drakaea glyptodon</i> Species of orchid endemic to Western Australia

Drakaea glyptodon, commonly known as king in his carriage is a species of orchid endemic to the south–west of Western Australia. It is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. It is the most common drakaea and has the widest distribution.

<i>Drakaea gracilis</i> Species of orchid endemic to Western Australia

Drakaea gracilis, commonly known as slender hammer orchid, is a species of orchid endemic to the south–west of Western Australia. It is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. It was first collected in 1900 but other names were given to it, including Drakaea elastica and D. fitzgeraldii. It was not until 2007 when studies of the drakaeas and their pollinators were carried out, that the present species was recognised as distinct.

<i>Drakaea isolata</i> Species of orchid endemic to Western Australia

Drakaea isolata, commonly known as lonely hammer orchid, is a species of orchid endemic to the south–west of Western Australia. It is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. It is known from only one population and has been declared "endangered" by the Australian government and "threatened" by the government of Western Australia. It was first collected in 1984 by Robert J. Bates. No other Drakaea species is found it the same area but the broad-billed duck orchid is found nearby.

<i>Drakaea livida</i> Species of orchid endemic to Western Australia

Drakaea livida, commonly known as warty hammer orchid, is a species of orchid endemic to the south–west of Western Australia. It is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. Although the species was formally described in 1842, the description was often later overlooked and other hammer orchids were given the name Drakea livida. It is now known to be, along with Drakaea glyptodon, one of the most widespread of the genus.

Drakaea micrantha, commonly known as the dwarf hammer orchid, is a species of orchid endemic to the south–west of Western Australia. It is similar to other hammer orchids in that it is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. It has a single silvery-grey, heart-shaped leaf with prominent green veins and a stem up to 30 centimetres (12 in) long. The species is only known from a scattered populations in the south west of the state and has been declared "vulnerable" by the Australian government and "threatened" by the government of Western Australia.

<i>Drakaea thynniphila</i> Species of orchid endemic to Western Australia

Drakaea thynniphila, commonly known as narrow-lipped hammer orchid is a species of orchid endemic to the south–west of Western Australia. It is pollinated by a single species of male thynnid wasp using sexual deception. The orchid's labellum is similar in shape and scent to a flightless female thynnid wasp. It is one of the more common drakaeas and is easily distinguished from the other species. The tiny lumps on its leaf along with the long flower that lacks a swollen labellum are diagnostic.

<i>Caleana dixonii</i> Species of flowering plant

Caleana dixonii, commonly known as the sandplain duck orchid is a rare species of orchid endemic to the south-west of Western Australia. It has a single smooth leaf and a single greenish yellow and fawn-coloured flower. It is distinguished by its flattened labellum with calli only near the tip of the labellum and its preference for growing on sandplains.

<i>Arthrochilus huntianus</i> Species of flowering plant

Arthrochilus huntianus, commonly known as common elbow orchid, is a flowering plant in the orchid family (Orchidaceae) and is endemic to south-eastern Australia. It has no leaves but an insect-like flower which has its labellum dangling like a lure away from the rest of the flower. Because of its thin, wiry stem and small, dull-coloured flowers, this orchid is difficult to locate. Like others in the genus, the flowers are pollinated by a species of thynnid wasp. Some authorities use the name Thynninorchis huntiana for this orchid.

Arthrochilus oreophilus, commonly known as the untidy elbow orchid, is a flowering plant in the orchid family (Orchidaceae) and is endemic to near the tip of Cape York in Queensland. It has two or three leaves at its base and up to seven pale green, insect-like flowers with reddish glands on its labellum.

Arthrochilus corinnae, commonly known as the swamp elbow orchid, is a flowering plant in the orchid family (Orchidaceae) and is endemic to the northern part of Cape York in Queensland. It has two or three dull bluish green leaves near its base and up to twelve pale green, insect-like flowers with shiny yellowish glands on its labellum.

References

  1. ↑ "Drakaea". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  2. 1 2 "Drakaea". FloraBase . Western Australian Government Department of Biodiversity, Conservation and Attractions.
  3. ↑ Turner, Rowland (1907). "A revision of the Thynnidae of Australia". Proceedings of the Linnean Society of New South Wales. 32: 206–290. doi: 10.5962/bhl.part.19569 . Retrieved 10 November 2015.
  4. ↑ Cingel, N. A. van der (2000). An atlas of orchid pollination : America, Africa, Asia and Australia. Rotterdam: Balkema. pp. 207–208. ISBN   9054104864 . Retrieved 10 November 2015.
  5. 1 2 Mitchell, Samille. "Orchid seductress ropes in unsuspecting males". Science Network, Western Australia. Retrieved 10 November 2015.
  6. ↑ Archer, William (16 July 2008). "King-in-his-carriage - Drakaea glyptodon". Esperance Wildflowers. Retrieved 10 November 2015.
  7. ↑ Phillips, R. D.; Bohman, B.; Anthony, J. M.; Krauss, S. L.; Dixon, K. W.; Peakall, R. (2015). "Mismatch in the distribution of floral ecotypes and pollinators: Insights into the evolution of sexually deceptive orchids". Journal of Evolutionary Biology. 28 (3): 601–612. doi: 10.1111/jeb.12593 . PMID   25619237. S2CID   27250034.
  8. ↑ Hopper, Stephen D.; Brown, Andrew P. (2004). "Robert Brown's Caladenia revisited, including a revision of its sister genera Cyanicula, Ericksonella and Pheladenia (Caladeniinae: Orchidaceae)". Australian Systematic Botany. 17 (2): 171–240. doi:10.1071/SB03002.
  9. 1 2 Hopper, Stephen D.; Brown, Andrew P. (2007). "A revision of Australia' s hammer orchids (Drakaea: Orchidaceae), with some field data on species-specific sexually deceived wasp pollinators". Australian Systematic Botany. 20 (3): 252–285. doi:10.1071/SB06033.
  10. ↑ "Drakaea elastica". APNI. Retrieved 10 November 2015.
  11. ↑ Lindley, John (1840). A Sketch of the Vegetation of the Swan River Colony. London: James Ridgway. p. 60. Retrieved 10 November 2015.
  12. ↑ Oden, Lesley Evans. "Three tricks orchids use to lure pollinating insects". British Broadcasting Corporation. Retrieved 10 November 2015.
  13. ↑ "Book of the Week: Sarah Ann Drake & Women's History Month". Biodiversity Heritage Library. 8 March 2012. Retrieved 10 November 2015.
  14. ↑ Paczkowska, Grazyna; Chapman, Alex R. (2000). The Western Australian flora : a descriptive catalogue. Perth: Wildflower Society of Western Australia. p. 85. ISBN   0646402439.
  15. ↑ "Conservation codes for Western Australian flora and fauna" (PDF). Government of Western Australia Department of Parks and Wildlife. Retrieved 19 September 2019.
  16. ↑ Phillips, Ryan D. "Landscape, pollinator and mycorrhizal specificity and their contribution to rarity in Drakaea (Hammer Orchids)" (PDF). School of Plant Biology, The University of Western Australia. Retrieved 10 November 2015.
  17. ↑ "Drakaea andrewsiae". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  18. ↑ "Drakaea concolor". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  19. ↑ "Drakaea confluens". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  20. ↑ "Drakaea elastica". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  21. ↑ "Drakaea glyptodon". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  22. ↑ "Drakaea gracilis". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  23. ↑ "Drakaea isolata". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  24. ↑ "Drakaea livida". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  25. ↑ "Drakaea micrantha". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  26. ↑ "Drakaea thynniphila". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
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