Caladenia longicauda subsp. eminens

Caladenia longicauda subsp. eminens, commonly known as the stark white spider orchid, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single hairy leaf and up to three large, bright white flowers with long, broad, spreading lateral sepals and petals, a relatively broad labellum with short, narrow teeth. It is a relatively common orchid found in a broad band, mainly between Tenterden and Jerramungup.

habit

C. longicauda subsp. eminens labellum detail

Stark white spider orchid
Caladenia longicauda subsp. eminens growing near Moora
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Diurideae
Genus:	Caladenia
Species:	C. longicauda
Subspecies:	C. l. subsp. eminens
Trinomial name
Caladenia longicauda subsp. eminens Hopper & A.P.Br.
Synonyms[1]
Arachnorchis longicauda subsp.eminens (Hopper & A.P.Br.) D.L.Jones & M.A.Clem.

Description

Caladenia longicauda subsp. eminens is a terrestrial, perennial, deciduous, herb with an underground tuber and a single hairy leaf, 120–250 mm (5–10 in) long and 5–15 mm (0.2–0.6 in) wide. Up to three, bright white flowers 100–180 mm (4–7 in) long and 80–120 mm (3–5 in) wide are borne on a spike 300–600 mm (10–20 in) tall. The dorsal sepal is erect, the lateral sepals are 90–140 mm (4–6 in) long and 6–12 mm (0.2–0.5 in) wide and the petals are 3–6 mm (0.1–0.2 in) wide. The labellum is white, more than 10 mm (0.4 in) wide and the column is a less than 10 mm (0.4 in) long. There are four or more rows of pale red calli in the centre of the labellum. Flowering occurs from August to early October.[2][3][4][5][6]

Taxonomy and naming

Caladenia longicauda was first formally described by John Lindley in 1840 and the description was published in A Sketch of the Vegetation of the Swan River Colony.[7] In 2001 Stephen Hopper and Andrew Brown described eleven subspecies, including subspecies eminens and the descriptions were published in Nuytsia.[1] The subspecies name (eminens) is a Latin word meaning “prominent", or "illustrious"[8] referring to the attractiveness of the flowers of this subspecies.[3]

Distribution and habitat

The stark white spider orchid mainly occurs between Tenterden and Jerramungup but is also found as far east as Esperance and as far north as Moora, in the Avon Wheatbelt, Coolgardie, Esperance Plains, Jarrah Forest, Mallee and Swan Coastal Plain biogeographic regions where it grows in wandoo (Eucalyptus wandoo) and yate (Eucalyptus cornuta) woodland.[2][3][4][9]

Conservation

Caladenia longicauda subsp. eminens is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.[9]

References

1. "Caladenia longicauda subsp. eminens". APNI. Retrieved 16 February 2017.
2. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. pp. 63–64. ISBN 1877069124.
3. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 87. ISBN 9780980296457.
4. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 102. ISBN 9780646562322.
5. Brown, Andrew P.; Brockman, Garry (2015). "New taxa of Caladenia (Orchidaceae) from south-west Western Australia". Nuytsia. 25: 87–88.
6. Archer, William. "Caladenia longicauda subsp. eminens". Esperance Wildflowers. Retrieved 16 February 2017.
7. "Caladenia longicauda". APNI. Retrieved 16 February 2017.
8. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 419.
9. "Caladenia longicauda subsp. eminens". FloraBase. Western Australian Government Department of Parks and Wildlife.