Caladenia caesarea subsp. transiens

Caladenia caesarea subsp. transiens, commonly known as the dwarf mustard spider orchid, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single spreading, hairy leaf and up to three small lemon-yellow flowers with red stripes. It is only known from a single small population near the town of Williams.

Dwarf mustard spider orchid

Priority One — Poorly Known Taxa (DEC)
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Caladenia
Species:
C. caesarea
Subspecies:
C. c. subsp. transiens
Trinomial name
Caladenia caesarea subsp. transiens

Description

Caladenia caesarea subsp. transiens is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, hairy leaf 10–15 cm (4–6 in) long and about 3 mm (0.1 in) wide. There are up to three lemon-yellow flowers borne on a stem 20–30 cm (8–10 in) high and each flower is 8–10 cm (3–4 in) long and 5–7 cm (2–3 in) wide. The lateral sepals and petals spread widely. The labellum is lemon-yellow coloured with brownish-red stripes, projects prominently with a curled tip, has an irregularly serrated edge and two rows of shiny yellow calli along its centre. Flowering occurs between September and October and is followed by a non-fleshy, dehiscent capsule containing a large number of seeds.[1][2][3]

Taxonomy and naming

This orchid was first formally described by Karel Domin in 1912 and given the name Caladenia filamentosa subsp. caesarea. Domin's description was published in Journal of the Linnean Society, Botany[4][5] but in 1989 Mark Clements and Stephen Hopper raised it to species status.[6][7] In 2001 Hopper and Andrew Brown described three subspecies, including subspecies transiens and the descriptions were published in Nuytsia.[8] The epithet (transiens) alludes to the shape of the labellum which is intermediate between that of Caladenia filamentosa and the other subspecies of Caladenia caesarea.[1]

Distribution and habitat

Dwarf mustard spider orchid only occurs near Williams in the Jarrah Forest biogeographic region where it grows under dense rock sheoak and wandoo trees.[1][2][9][10]

Conservation

Caladenia caesarea subsp. transiens is classified as "Priority One" by the Government of Western Australia Department of Parks and Wildlife,[9] meaning that it is known from only one or a few locations which are potentially at risk.[11]

References
  1. 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. 54. ISBN 9780980348149.
  2. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 77. ISBN 9780646562322.
  3. "Caladenia". Royal Botanic Gardens Victoria. Retrieved 31 October 2016.
  4. "Caladenia filamentosa subsp. caesarea". APNI. Retrieved 31 October 2016.
  5. Domin, Karel (1912). "Flora of Western and North-Western Australia". Journal of the Linnean Society, Botany. 41: 251. Retrieved 31 October 2016.
  6. "Caladenia caesarea". APNI. Retrieved 31 October 2016.
  7. Clements, Mark Alwyn; Hopper, Stephen (1989). "Catalogue of Australian Orchidaceae". Australian Orchid Research. 1: 21.
  8. "Caladenia caesarea subsp. transiens". APNI. Retrieved 1 November 2016.
  9. "Caladenia caesarea subsp. transiens". FloraBase. Western Australian Government Department of Parks and Wildlife.
  10. Paczkowska, Grazyna; Chapman, Alex R. (2000). The Western Australian flora : a descriptive catalogue. Perth: Wildflower Society of Western Australia. p. 76. ISBN 0646402439.
  11. "Conservation codes for Western Australian Flora and Fauna" (PDF). Government of Western Australia Department of Parks and Wildlife. Retrieved 8 December 2015.
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