Thelymitra occidentalis

Thelymitra occidentalis, commonly called the western azure sun orchid[2] or rimmed orchid,[3] is a species of orchid in the family Orchidaceae and is endemic to the south-west of Australia. It has a single erect, fleshy, channelled, dark green leaf and up to fifteen blue flowers with darker blue veins and sometimes flushed with pink. The lobe on top of the anther has a wavy, yellow crest.

Western azure sun orchid
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Thelymitra
Species:
T. occidentalis
Binomial name
Thelymitra occidentalis
Jeanes[1]

Description

Thelymitra occidentalis is a tuberous, perennial herb with a single erect, fleshy, channelled, dark green, linear to lance-shaped leaf 80–250 mm (3–10 in) long and 3–10 mm (0.1–0.4 in) wide with a purplish base. Between two and fifteen blue flowers with darker blue lines and often flushed with pink, 15–32 mm (0.6–1 in) wide are borne on a flowering stem 120–400 mm (5–20 in) tall. The sepals and petals are 7–15 mm (0.3–0.6 in) long and 3–6 mm (0.1–0.2 in) wide. The column is whitish or pale blue, 3–5 mm (0.1–0.2 in) long and 2–3 mm (0.08–0.1 in) wide with flanges on the sides. The lobe on the top of the anther is purplish black with a wavy yellow crest and the side lobes have mop-like tufts of purple or white hairs. The flowers are insect pollinated and open on hot days. Flowering occurs from September to November.[2][3][4][5]

Taxonomy and naming

Thelymitra occidentalis was first formally described in 2001 by Jeff Jeanes and the description was published in Muelleria from a specimen collected near Cranbrook.[6] The specific epithet (occidentalis) is a Latin word meaning "western"[7] referring to the distribution of this species compared to the similar T. azurea.[5]

Distribution and habitat

The western azure sun orchid grows in heath and woodland, often near rock outcrops and near winter-wet depressions. It is found between Cranbrook in Western Australia and Eyre in South Australia. It has also been recorded on the Eyre Peninsula in South Australia.[2][3][8]

Conservation

Thelymitra latiloba is classified as "not threatened" in Western Australia by the Western Australian Government Department of Parks and Wildlife.[8]

References
  1. "Thelymitra occidentalis". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  2. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 431. ISBN 9780980296457.
  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. 245. ISBN 1877069124.
  4. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 310. ISBN 9780646562322.
  5. Jeanes, Jeffrey A. (2001). "Resolution of the Thelymitra canaliculata R.Br. (Orchidaceae) complex in southern Australia" (PDF). Muelleria. 15: 85–88. Retrieved 29 May 2018.
  6. "Thelymitra occidentalis". APNI. Retrieved 29 May 2018.
  7. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 853.
  8. "Thelymitra occidentalis". FloraBase. Western Australian Government Department of Biodiversity, Conservation and Attractions.
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