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Diuris tricolor, commonly known as the long-tailed donkey orchid[2] or pine donkey orchid,[3] is a species of orchid that is endemic to New South Wales, although a single plant has been found in Victoria. It has up to three grass-like leaves and up to six orange-coloured to yellow flowers with white and purplish tints. The lateral sepals are unusually long.

Long-tailed donkey orchid
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Diurideae
Genus:	Diuris
Species:	D. tricolor
Binomial name
Diuris tricolor Fitzg.[1]
Synonyms[1]
Diuris sheaffiana Fitzg. Diuris colemaniae Rupp

Description

Diuris tricolor is a tuberous, perennial herb with up to three linear leaves 200–300 mm (8–10 in) long, 3–4 mm (0.1–0.2 in) wide and folded lengthwise. Between two and six orange-coloured to yellow flowers with white and purplish tints, 25–30 mm (0.98–1.2 in) wide are borne on a flowering stem 200–400 mm (8–20 in) tall. The dorsal sepal curves upwards, 10–15 mm (0.4–0.6 in) long, 6–9 mm (0.2–0.4 in) wide and broadly egg-shaped. The lateral sepals are narrow linear, 20–65 mm (0.8–3 in) long, much less than 1 mm (0.04 in) wide and turned downwards. The petals are more or less erect or turned backwards, egg-shaped to elliptic, the blade 10–16 mm (0.4–0.6 in) long and 6–10 mm (0.2–0.4 in) wide on a reddish purple stalk 3–7 mm (0.1–0.3 in) long. The labellum is 8–12 mm (0.3–0.5 in) long and has three lobes. The centre lobe is egg-shaped, 6–9 mm (0.2–0.4 in) long and wide with a central ridge. The side lobes are 3–4.5 mm (0.1–0.2 in) long and about 2 mm (0.08 in) wide. There are two callus ridges about 4 mm (0.2 in) long near the mid-line of the labellum. Flowering occurs from September to November.[2][4][5]

Taxonomy and naming

Diuris tricolor was first formally described in 1885 by Robert FitzGerald and the description was published in the Journal of Botany, British and Foreign.[6][7] The specific epithet (tricolor) is derived from the Latin prefix tri- meaning "three",[8]^: 798 and color meaning "hue", "tint" or "complexion".[8]^: 219

In 1940, Herman Rupp described D. colemaniae[9] in honour of Edith Coleman and which he noted had shorter lateral sepals and a "quite different" labellum.[10] Diuris colemaniae is now regarded as a synonym of D. tricolor.[1]

Distribution

The long-tailed donkey orchid grows in grassland and forest in New South Wales, sporadically distributed south from Deepwater and in the Australian Capital Territory. A single specimen has been recorded in Victoria, just south of the border.[2][3][4]

Conservation

Diuris tricolor is classed as Vulnerable in New South Wales under the Biodiversity Conservation Act 2016.[3] The main threats to the species are habitat alteration and grazing by rabbits and goats.[3]

References

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