Diuris palustris, commonly known as the swamp doubletail or swamp diuris is a species of orchid which is endemic to south-eastern Australia. It has a tuft of between eight and ten twisted leaves and up to four yellow flowers with brown spots and blotches marks and blotches.
Diuris palustris is a tuberous, perennial herb with a tuft of between eight and ten twisted, linear leaves NaNsigfig=1NaNsigfig=1 long, NaNsigfig=2NaNsigfig=2 wide and folded lengthwise. Up to four flowers NaNsigfig=1NaNsigfig=1 wide are borne on a flowering stem NaNsigfig=1NaNsigfig=1 tall. The flowers are yellow with dark brown spots and blotches. The dorsal sepal is erect, curved backwards near the tip, egg-shaped, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=2NaNsigfig=2 wide. The lateral sepals are green, NaNsigfig=1NaNsigfig=1 long, about 2sigfig=1NaNsigfig=1 wide, turned downwards and parallel to each other. The petals are erect to curved backwards, with an egg-shaped blade NaNsigfig=2NaNsigfig=2 long and NaNsigfig=1NaNsigfig=1 wide on a dark reddish brown stalk NaNsigfig=1NaNsigfig=1 long. The labellum is NaNsigfig=1NaNsigfig=1 long and has three lobes. The centre lobe is spatula-shaped, NaNsigfig=1NaNsigfig=1 wide and the side lobes are erect, oval, NaNsigfig=2NaNsigfig=2 long and NaNsigfig=1NaNsigfig=1 wide with rounded teeth near the tip. There are two ridged calli NaNsigfig=2NaNsigfig=2 long in the mid-line of the labellum. Flowering occurs from August to October.[1] [2] [3]
Diuris palustris was first formally described in 1840 by John Lindley and the description was published in his book, The Genera and Species of Orchidaceous Plants.[4] [5] The specific epithet (palustris) is a Latin word meaning "marshy" or "boggy".[6]
The swamp doubletail is found in New South Wales, Victoria, Tasmania and South Australia where it is most common. It grows in moist or wet soil in forest, Callitris woodland and grassland.
Diuris palustris is classed as "vulnerable" under the Victorian Flora and Fauna Guarantee Act 1988 and as "endangered" under the Tasmanian Threatened Species Protection Act 1995.[7]