Rhizanthella gardneri

Last updated

Western underground orchid
Rhizanthella gardneri -- Fred Hort.jpg
Rhizanthella gardneri
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Rhizanthella
Species:
R. gardneri
Binomial name
Rhizanthella gardneri

Rhizanthella gardneri, commonly known as western underground orchid, [2] is a species of flowering plant in the orchid family and is endemic to the southwest of Western Australia. It is a herb that spends its entire life cycle, including flowering, at or below the soil surface. A head of up to 100 small reddish to cream-coloured, inward facing flowers surrounded by large, cream-coloured bracts with a horizontal rhizome is produced between May and July.

Contents

Description

Rhizanthella gardneri is a leafless, sympodial herb with a horizontal rhizome 60–120 mm (2.4–4.7 in) below the soil surface. Beginning in late May to early June, the plant produces up to 100 small, inward-facing pinkish to deep red and cream coloured flowers 4–5 mm (0.16–0.20 in) wide, surrounded by six to twelve pinkish-cream bracts. The bracts curve over the flowers, forming a tulip-like head and leaving a small opening at, or a few millimetres above the soil surface. After pollination, each flower produces a fleshy, berry-like fruit containing up to 150 seeds. Unlike the capsules of other orchids that produce minute, dust-like seeds dispersed by the wind, this species produces indehiscent fruit. [3] [4] [5]

Discovery, taxonomy and naming

John Trott discovered the first specimen of R. gardneri during ploughing operations in May 1928 on his farm near Corrigin. The discovery generated such excitement that a wax model was toured around the British Isles. [6] Specimens were found a further six times in similar circumstances between the Corrigin and Dowerin areas, until 1959. The next confirmed sighting was by John McGuiness near Munglinup in 1979, of plants in their natural habitat. In 1981 and 1982, surveys in the Munglinup area located more than one hundred flowering specimens. [2] [4] [5] The Munglinup population is now regarded as the separate species, Rhizanthella johnstonii . [7]

Rhizanthella gardneri was first formally described in 1928 by Richard Sanders Rogers in the Journal of the Royal Society of Western Australia from specimens collected near Corrigin in May of the same year. [8] The specific epithet (gardneri) honours Charles Gardner, assistant botanist to the Western Australian Government at that time. [9]

Distribution and habitat

Rhizanthella gardneri is only known from the Avon Wheatbelt biogeographic region of Western Australia, where it grows in association with broom honeymyrtle ( Melaleuca uncinata ), between Corrigin and Babakin. [3] [10] [7]

Ecology

As with other orchids in the genus Rhizanthella, all parts of the life cycle of R. gardneri, including flowering, are subterranean. The orchid obtains its energy and nutrients as a myco-heterotroph via mycorrhizal fungi that form associations with the roots of broombush species including M. uncinata, M. scalena and M. hamata . [6] The fungus involved is thought to be Thanatephorus gardneri. [11] [12] [13]

The flowers of R. gardneri are subterranean but the heads crack open the soil surface as they mature, and sometimes the tips of the bracts protrude through the leaf litter, leaving a small opening through which pollinators may enter. Termites and ants have been seen to enter the flower heads. The orchid's seeds are too large to be dispersed by the wind and it is possible that the succulent fruit is eaten by small mammals and the seeds passed out of their faeces. [2] [4]

Conservation status

The species is classified as "critically endangered" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999 and as "Threatened Flora (Declared Rare Flora — Extant)" by the Department of Environment and Conservation (Western Australia). [5] [10]

Much of the central and southern Wheatbelt of Western Australia has been cleared for agriculture, or affected by drought, resulting in the loss of broombush habitat or a reduction in the level of bark and leaf litter necessary to protect the underground orchid and a reduction in the area suitable for translocation. The main threats to the species include lack of suitable habitat, degraded habitat, drought and rising soil salinity. [5]

Three of the known populations of Rhizanthella gardneri are protected within nature reserves, [3] and a concerted initiative has been launched to safeguard this species for future generations. [6] A partnership between the Millennium Seed Bank of the Royal Botanic Gardens, Kew, Australia's Endangered Species Program and Perth's Kings Park and Botanic Gardens are undertaking DNA fingerprinting and seed-banking of this rare orchid in an attempt to establish a propagation programme. [6]

Related Research Articles

<i>Rhizanthella slateri</i> Species of orchid

Rhizanthella slateri, commonly known as the eastern underground orchid, is a species of flowering plant in the orchid family and is endemic to New South Wales. It is a mycoheterotrophic herb that spends most of its life under the soil surface, its flowers only sometimes appearing a few millimetres about ground level.

<span class="mw-page-title-main">Babakin, Western Australia</span> Town in Western Australia

Babakin is a small town located in the Wheatbelt region of Western Australia between the towns of Bruce Rock and Corrigin. At the 2021 census the population of Babakin was 56. Facilities in the town include a school, shop, hall and sporting facilities.

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

Rhizanthella, commonly known as underground orchids, is a genus of flowering plants in the orchid family, Orchidaceae and is endemic to Australia. All are leafless, living underground in symbiosis with mycorrhizal fungi. The inflorescence is a head of flowers held at, or just above the ground but mostly covered by soil or leaf litter and little is known about the mechanism of pollination.

<i>Grevillea scapigera</i> Species of shrub in the family Proteaceae endemic to Western Australia

Grevillea scapigera, commonly known as Corrigin grevillea, is a species of flowering plant in the family Proteaceae and is endemic to a small area of the south-west of Western Australia. It is a prostrate to weakly ascending, suckering shrub with divided leaves, the end lobes broadly triangular and sharply-pointed, and spikes of white to cream-coloured flowers held above the foliage.

<i>Melaleuca uncinata</i> Species of plant

Melaleuca uncinata, commonly known as broombush, broom honeymyrtle or brushwood, is a plant in the paperbark family native to southern Australia. It is harvested from the wild, and grown in plantations, for broombush fencing. The Noongar names for the plant are kwytyat and yilbarra.

<i>Caladenia arenicola</i> Species of orchid

Caladenia arenicola, commonly known as the carousel spider orchid, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single erect, hairy leaf and up to three red, white and green flowers on a flowering stem up to 60 cm (20 in) high. It is a common species on the Swan Coastal Plain, where it grows in sandy soil under trees.

<i>Caladenia arrecta</i> Species of orchid

Caladenia arrecta, commonly known as the reaching spider orchid, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single erect, hairy leaf and up to three red, yellow and green flowers on a flowering stem up to 35 cm (10 in) high. It is distinguished from the similar C. longiclavata and C. magniclavata by its upswept petals and distinctive calli. Although not common, it is widespread in south-eastern coastal areas.

Caladenia bicalliata is a species of flowering plant in the orchid family Orchidaceae and is native to the south-west of Western Australia and coastal areas of South Australia. It has a single erect, hairy leaf and one or two cream-coloured flowers. There are two subspecies differing in the size and colour of the flowers.

Caladenia citrina, commonly known as the Margaret River spider orchid, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single erect, hairy leaf and up to three lemon-yellow flowers. It has a narrow distribution in the far south-west corner of Western Australia.

<i>Caladenia excelsa</i> Species of orchid

Caladenia excelsa, commonly known as the giant spider orchid, is a species of orchid endemic to a small area in the south-west of Western Australia. It is a rare species with a single, hairy leaf and up to three cream-coloured to greenish-cream flowers with long, drooping sepals and petals. It is one of the tallest spider orchids in Western Australia and, with Caladenia splendens, has the largest flowers of any Western Australian orchid.

<i>Caladenia fluvialis</i> Species of orchid

Caladenia fluvialis, commonly known as the Brookton Highway spider orchid is a species of orchid endemic to the south-west of Western Australia. It is a recently discovered orchid with a single hairy leaf and one or two cream-yellow flowers with red markings on the labellum.

Caladenia hiemalis, commonly known as the dwarf common spider orchid is a species of orchid endemic to the south-west of Western Australia. It has a single, hairy leaf and one or two, cream-coloured flowers with a small, red-striped labellum. It has an early flowering period and its flowering is stimulated by summer fires.

<i>Caladenia huegelii</i> Species of orchid

Caladenia huegelii, commonly known as the grand spider orchid is a species of orchid endemic to the south-west of Western Australia. It has a single, hairy leaf and up to three relatively large red, green and cream-coloured flowers which have "split-hairs" on the sides of the labellum.

<i>Caladenia radialis</i> Species of orchid

Caladenia radialis, commonly known as the drooping spider orchid, is a species of orchid endemic to the south-west of Western Australia. It has a single erect, hairy leaf and one or two red and cream-coloured flowers. In good seasons it forms clumps of up to ten plants.

Caladenia petrensis, commonly known as the rock spider orchid is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single erect, hairy leaf and up to three pale yellow flowers with drooping lateral sepals and petals.

<i>Caladenia vulgata</i> Species of orchid

Caladenia vulgata, commonly known as the common spider orchid, is a species of orchid endemic to the south-west of Western Australia. It is a relatively common and widespread orchid with a single erect, hairy leaf and up to three creamy-white flowers. There is some variation in the species, both in flower colour and growth habit.

Pterostylis brunneola, commonly known as the giant snail orchid, is a species of orchid endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a large rosette of leaves flat on the ground and flowering plants have a single distinctive white flower with pale fawn stripes and have leaves on the flowering spike. This species often forms large colonies, sometimes with Caladenia species.

Rhizanthella speciosa is a species of flowering plant in the orchid family and is endemic to Barrington Tops in New South Wales. It is a mycoheterotrophic herb that spends its entire life cycle, including flowering, at or below the soil surface. As at September 2020, R. speciosa has not yet been accepted as a valid name by the World Checklist of Selected Plant Families or the Australian Plant Census.

<i>Rhizanthella johnstonii</i> Species of orchid

Rhizanthella johnstonii, commonly known as south coast underground orchid, is a species of flowering plant in the orchid family and is endemic to the southwest of Western Australia. It is a subterranean herb that has a horizontal rhizome and a head of up to sixty small white flowers with a pink tinge, surrounded by relatively large, cream-coloured to pale pinkish cream bracts.

Rhizanthella omissa is a species of flowering plant in the orchid family and is found in the Lamington National Park in Queensland. It is a subterranean herb that grows in casuarina forest and flowers underground. It was first formally described in 2006 by David Jones and Mark Clements in the journal The Orchadian. The species is listed as "endangered" under the Queensland Government Nature Conservation Act 1992.

References

  1. "Rhizanthella gardneri". Australian Plant Census. Retrieved 25 September 2019.
  2. 1 2 3 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. pp. 408–409. ISBN   9780980348149.
  3. 1 2 3 Hágsater, E. and Dumont, V. (1996) Orchids: Status Survey and Conservation Action Plan. IUCN/SSC Orchid Specialist Group, IUCN, Gland.
  4. 1 2 3 Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. pp. 386–389. ISBN   9780646562322.
  5. 1 2 3 4 Brown, Andrew; Batty, Andrew; Brundrett, Mark; Dixon, Kingsley. "Underground Orchid (Rhizanthella gardneri) - Interim Recovery Plant 2003–2008" (PDF). Australian Government Department of the Environment. Retrieved 26 September 2020.
  6. 1 2 3 4 Dixon, K. (2003). "Underground orchids on the edge". Plant Talk (31): 34–35.
  7. 1 2 Dixon, Kingsley W.; Christenhusz, Maarten J. M. (12 January 2018). "Flowering in darkness: a new species of subterranean orchid Rhizanthella (Orchidaceae; Orchidoideae; Diurideae) from Western Australia". Phytotaxa. 334 (1): 75–79. doi:10.11646/phytotaxa.334.1.12.
  8. "Rhizanthella gardneri". APNI. Retrieved 26 September 2020.
  9. Rogers, Richard Sanders (1928). "A New Genus of Australian Orchid". Journal of the Royal Society of Western Australia. 15 (1): 1–4. Retrieved 26 September 2020.
  10. 1 2 "Rhizanthella gardneri". FloraBase . Western Australian Government Department of Biodiversity, Conservation and Attractions.
  11. "Western Australia's Incredible Underground Orchid". ScienceDaily.com. ScienceDaily. 9 February 2011. Retrieved 10 February 2011.
  12. Bougoure, Jeremy; Ludwig, Martha; Brundrett, Mark; Grierson, Pauline (October 2009). "Identity and specificity of the fungi forming mycorrhizas with the rare mycoheterotrophic orchid Rhizanthella gardneri". Mycological Research. 113 (10): 1097–1106. doi:10.1016/j.mycres.2009.07.007. PMID   19619652.
  13. Bougoure, Jeremy; Brundrett, Mark; Brown, Andrew; Grierson, Pauline F. (2008). "Habitat characteristics of the rare underground orchid Rhizanthella gardneri". Australian Journal of Botany. 56 (6): 501–511. doi:10.1071/BT08031.

Further reading

  1. Reader's Digest Ltd. (1989). Facts and Fallacies - Stories of the Strange and Unusual. Reader's Digest Ltd. Page 39. ISBN   0-86438-087-9.
  2. Jones, David L. (2006). A complete guide to native orchids of Australia: including the island territories. Frenchs Forest. ISBN   1-877069-12-4.