Caleana dixonii

Caleana dixonii, commonly known as the sandplain duck orchid[3] 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.

Sandplain duck orchid

Declared rare (DEC)
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Caleana
Species:
C. dixonii
Binomial name
Caleana dixonii
Synonyms[2]

Description

Caleana dixonii has a single smooth, dull green to dull red leaf, 20–40 mm (0.8–2 in) long and 4–6 mm (0.16–0.24 in) wide. The leaf is usually withered by flowering time. Usually only one greenish-yellow and fawn-coloured flower, 20–25 mm (0.8–1 in) long and 12–16 mm (0.5–0.6 in) wide is borne on a flowering stem 130–180 mm (5–7 in) high. The dorsal sepal, lateral sepals and petals are narrow and hang downwards with the dorsal sepal pressed against the column which has broad wings, forming a bucket-like shape. About one-third of the outer part of the labellum is covered with glossy black glands or calli and the labellum has a flattened top. Flowering occurs from late October to early December.[3][4]

Taxonomy and naming

The sandplain duck orchid was first formally described in 2006 by Stephen Hopper and Andrew Brown who gave it the name Paracaleana dixonii. The description was published in Australian Systematic Botany.[5] In 2014, based on molecular studies, Joseph Miller and Mark Clements transferred all the species previously in Paracaleana to Caleana so that the present species became Caleana dixonii.[1][6] The specific epithet (dixonii) honours Kingsley Dixon, the science director at Kings Park and Botanic Garden, who was the first to recognise this species as distinct.[3][4]

Distribution and habitat

Caleana dixonii grows in sandy shrubland between Dongara and the Moore River National Park in the Geraldton Sandplains and Swan Coastal Plain biogeographic regions.[3][4][7]

Conservation

Caleana dixonii (as Paracaleana dixonii) is classified as "Threatened Flora (Declared Rare Flora — Extant)" by the Department of Environment and Conservation (Western Australia)[7]

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References
  1. "Caleana dixonii". APNI. Retrieved 15 April 2018.
  2. "Caleana dixonii". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  3. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 252. ISBN 9780646562322.
  4. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 301. ISBN 9780980296457.
  5. "Paracaleana dixonii". APNI. Retrieved 15 April 2018.
  6. Miller, Joseph T.; Clements, Mark A. (2014). "Molecular phylogenetic analyses of Drakaeinae: Diurideae (Orchidaceae) based on DNA sequences of the internal transcribed spacer region". Australian Systematic Botany. 27 (1): 3–22. doi:10.1071/SB13036. Retrieved 15 April 2018.
  7. "Paracaleana dixonii". FloraBase. Western Australian Government Department of Parks and Wildlife.
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