Caladenia petrensis
Caladenia petrensis, commonly known as the rock spider orchid is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a single erect, hairy leaf and up to three pale yellow flowers with drooping lateral sepals and petals. Description. "Caladenia petrensis" is a terrestrial, perennial, deciduous, herb with an underground tuber. It is sometimes found as a solitary plant or otherwise in small clumps. It has a single erect, hairy leaf long, wide and blotched with reddish-purple near its base. Up to three flowers long and wide are  borne on a spike tall. The flowers are cream-coloured to pale yellow with dark red lines and blotches. The dorsal sepal is erect, long, wide and curves slightly forwards. The sepals and petals are linear to lance-shaped near their base, then suddenly narrow to a dark brown, thread-like tip covered with glandular hairs. The lateral sepals are long, wide and spread widely but with drooping tips. The petals are long, wide and arranged like the lateral sepals. The labellum is pale yellowish-white with red stripes, long, wide with forward-facing serrations on the sides. The tip  of the labellum curves downwards and there are two rows of anvil-shaped calli along its centre. Flowering occurs from late July to September. Taxonomy and naming. "Caladenia petrensis" was first formally described by Andrew Brown and Garry Brockman in 2007 from a specimen collected near Rothsay. The description was published in Nuytsia. The specific epithet ("petrensis") is a Latin word meaning "among rocks" referring to the rocky habitat where this species grows. Distribution and habitat. The rock spider orchid is found between Canna and Paynes Find in the Avon Wheatbelt, Geraldton Sandplains and Yalgoo biogeographic regions where it grows  in seasonally moist soils on rocky hills. Conservation. "Caladenia petrensis" is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.