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Windswept spider-orchid
Conservation status
Endangered  (EPBC Act)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Diurideae
Genus:	Caladenia
Species:	C. dienema
Binomial name
Caladenia dienema D.L.Jones
Synonyms
Arachnorchis dienema (D.L.Jones) D.L.Jones & M.A.Clem. Calonemorchis dienema (D.L.Jones) Szlach.

Caladenia dienema, commonly known as the windswept spider-orchid, is a plant in the orchid family Orchidaceae and is endemic to Tasmania. It is a ground orchid with a single, hairy leaf and a single, variably-coloured, usually dark red flower on a thin, wiry stem 5–12 cm (2–5 in) high.

Description

Caladenia dienema is a terrestrial, perennial, deciduous, herb with an underground tuber and which grows singly or in small, loose groups. It has a single, hairy, narrow lance-shaped leaf, 4–9 cm (2–4 in) long and 3–7 mm (0.1–0.3 in) wide. The leaf is dull green and has purple blotches near its base.

One or two flowers, 60–90 mm (2–4 in) across, are borne on a thin, wiry, hairy spike 5–12 cm (2–5 in) high. The flowers are variably coloured, usually dark red but may be almost white, yellow or from pale to deep red, and usually have darker red lines. The dorsal sepal is linear to oblong, 40–60 mm (1.6–2.4 in) long, 2–3.5 mm (0.08–0.1 in) wide but tapers to a thin, blackish glandular tip. The lateral sepals and petals are a similar size and shape to the dorsal sepal and end with a similar tip, although the petals are slightly narrower. The lateral sepals and petals spread widely and are turned downwards to drooping. The labellum is broadly lance-shaped to egg-shaped when flattened and is coiled forward at the tip, 13–20 mm (0.5–0.8 in) long and 7–11 mm (0.3–0.4 in) wide. There are 13 to 18 pairs of narrow, linear teeth up to 2 mm (0.08 in) along the edges of the labellum. There are four to six rows of erect, hockey stick-shaped calli along the centre of the labellum. The column is 12–14 mm (0.5–0.6 in) long, about 1.5 mm (0.06 in) wide and yellow and has broad wings. Flowering occurs in October and November and is followed by the fruit which is a reddish capsule 12–18 mm (0.5–0.7 in) long.

Taxonomy and naming

Caladenia dienema was first formally described by David L. Jones in 1998 and the description was published in Australian Orchid Research. The specific epithet (dienema) refers to the nature of this orchid's habitat.

Distribution and habitat

Elegant caladenia grows in windswept, low heath and in rocky areas in heathy woodland. It occurs in areas near the coast of Tasmania, north of the Pieman River, especially near Temma and Marrawah, although it was previously recorded on the north-west coast near Stanley.

Conservation

Caladenia behrii is classified as "Endangered" under the Tasmanian Government Threatened Species Protection Act 1995 and the Australian Government Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The main threats to the species are land clearing, agricultural practices, recreational activities and inappropriate fire regimes.

References

1. ^ "Caladenia dienema". APNI. Retrieved 15 January 2017.
2. ^ Jones, David L. (1998). "Contributions to Tasmanian Orchidology (2): A taxonomic review of Caladenia R.Br. in Tasmania". Australian Orchid Research. 3: 28–29.
3. ^ "Caladenia dienema - windswept spider orchid" (PDF). Government of Tasmania Department of Primary Industries, Parks, Water and Environment. Retrieved 15 January 2017.
4. ^ "Approved Conservation Advice for Caladenia dienema (windswept spider-orchid)" (PDF). Australian Government Department of the Environment. Retrieved 15 January 2017.

• EPBC Act endangered biota
• Caladenia
• Plants described in 1998
• Endemic orchids of Australia
• Orchids of Tasmania
• Taxa named by David L. Jones (botanist)