Caladenia osmera is a plant in the orchid family Orchidaceae and is endemic to south-eastern Australia. It is a ground orchid with a single leaf and one or two greenish-cream flowers with pink stripes and which has a sharp odour resembling burnt plastic.
Caladenia osmera is a terrestrial, perennial, deciduous, herb with an underground tuber and a single leaf, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. One or two greenish-cream to cream-coloured flowers with pink stripes and blotches are borne on a spike NaNsigfig=1NaNsigfig=1 tall. The flowers have a sharp odour resembling the smell of burnt plastic. The sepals and petals have narrow, dark red, club-like glandular tips NaNsigfig=1NaNsigfig=1 long. The sepals and petals are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide with the petals shorter than the sepals. The sepals and petals spread widely and horizontally or curve downwards. The labellum is greenish-cream with a dark red tip and is NaNsigfig=1NaNsigfig=1 long and NaNsigfig=2NaNsigfig=2 wide. The sides of the labellum curve upwards and have linear teeth up to 25sigfig=1NaNsigfig=1 long, decreasing in size towards the tip. There are four or six rows of calli about 1sigfig=1NaNsigfig=1 long near the base of the labellum and tapering towards the tip. Flowering occurs in September and October.[1]
This orchid was first formally described in 2006 by David Jones and given the name Arachnorchis osmera. The description was published in Australian Orchid Research.[2] In 2007 Gary Backhouse changed the name to Caladenia osmera.[3] The specific epithet (osmera) is derived from the Ancient Greek word osme meaning "smell" or "odour"[4] referring to the strong floral scent of this species.[5]
Caladenia osmera is only known from areas east of Bruthen where it grows in tall montane forest. It probably also occurs on the Southern Tablelands of New South Wales.[6]
Caladenia osmera is listed as "vulnerable" under the Victorian Flora and Fauna Guarantee Act 1988.