Caladenia bicalliata subsp. bicalliata, commonly known as the limestone spider orchid or dwarf limestone spider orchid, is a plant in the orchid family Orchidaceae and is native to the south-west of Western Australia and coastal areas of South Australia. It has a single erect, hairy leaf and one or two cream-coloured flowers with reddish-brown tips.
Caladenia bicalliata subsp. bicalliata is a terrestrial, perennial, deciduous, herb with an underground tuber and which occurs singly or in small clumps. It has a single erect, very hairy, linear to lance-shaped leaf, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The inflorescence is a raceme, NaNsigfig=1NaNsigfig=1 high with one or two flowers, each flower NaNsigfig=1NaNsigfig=1 long and 4sigfig=1NaNsigfig=1 wide. The dorsal sepal is about 2sigfig=1NaNsigfig=1 long and abruptly narrows about one-third of its length from the base. The lateral sepals and petals are cream or greenish-cream, much shorter than those of the similar C. abbreviata and C. evanescens and have reddish-brown tips. The lateral sepals are less than 2sigfig=1NaNsigfig=1 long and thread-like for about half their length and the petals are about the same length and gradually taper to a thread-like tip. The labellum is egg-shaped, about 7sigfig=1NaNsigfig=1 long, 5sigfig=1NaNsigfig=1 wide and white with red stripes. The edge of the labellum is serrated and there are two rows of white-tipped calli along its centre. Flowering occurs from August to early October, however the flowers are often open for only one or two days and sometimes self-pollinate and do not open at all.[1] [2] [3] [4]
Caladenia bicalliata was first formally described by Richard Rogers in 1909[5] but in 2001 Stephen Hopper and Andrew Brown described two subspecies, including subspecies bicalliata and the description of the two subspecies was published in Nuytsia[6] The specific epithet (bicalliata) is a derived from the Latin bi- meaning "two", callus meaning "a callus" and -atus indicating possession, referring to the two pairs of rows of calli on the labellum.[7]
Limestone spider orchid occurs in a narrow coastal strip, growing in calcareous soil between Kalbarri and Esperance in Western Australia and along the south-east coast but sometimes up to 100sigfig=1NaNsigfig=1 inland in South Australia.[8]
Caladenia bicalliata subsp. bicalliata is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.