Diuris aequalis


Diuris aequalis, commonly called the buttercup doubletail, is a species of orchid which is endemic to New South Wales. It has two rolled leaves and spikes of two to five golden-yellow to orange flowers and is classified as "vulnerable".

Description

Diuris aequalis is a tuberous, perennial herb, usually growing to a height of. There are two linear leaves arising from the base of the plant, each leaf long, wide and rolled so that the sides of the leaf face each other. There are between two and five golden-yellow to orange flowers arranged on a raceme, usually without spots, each about wide. The sepal is broadly egg-shaped to almost circular, long, wide above the flower. The sepals are linear to lance-shaped, long, wide, sickle-shaped and green. The petals are erect, ear-like above the flower, long and wide. The labellum is long, wide and has three lobes, the medial lobe ridged in its centre and has two broad calli about long. Flowering occurs between October and December, following which the leaves die back to be replaced prior to the next flowering.

Taxonomy and naming

Diuris aequalis was first formally described in 1876 by Robert D. FitzGerald from a previously unpublished description by Ferdinand von Mueller. The description was published in Fitzgerald's book, Australian Orchids. The specific epithet is a Latin word meaning "like", "same" or "uniform".

Distribution and habitat

Buttercup doubletail orchid occurs on the ranges and tablelands of New South Wales between Braidwood and the Kanangra-Boyd National Park where it grows in forest and low open woodland with a grassy understory, often on gentle slopes.

Conservation

Only about 200 individual plants of D. aequalis are known, mostly on roadsides and on agricultural land. It is listed as "Vulnerable" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999. The threats to its survival include land clearing, grazing, road maintenance and illegal rubbish dumping.
It was one of the plants targeted in the 2015 Save a Species Walk.