Calochilus caesius
{{Short description|Species of orchid}}
{{Use Australian English|date=July 2024}}
{{Use dmy dates|date=June 2018}}
{{Speciesbox
| name = Blue beard orchid
| image =
| image_caption =
| genus = Calochilus
| species = caesius
| authority = D.L.Jones{{WCSP | 223434 | Calochilus caesius}}
| synonyms =
}}
Calochilus caesius, commonly known as the blue beard orchid, is a species of orchid endemic to the Northern Territory in Australia. It has a single leaf which is not present during flowering and up to five pale green, very short-lived flowers with a bluish-red "beard".
Description
Calochilus caesius is a terrestrial, perennial, deciduous, herb with an underground tuber and a single leaf {{convert|100-200|mm|in|sigfig=1|abbr=on}} long and {{convert|3-5|mm|in|sigfig=1|abbr=on}} wide but which is not present during flowering. Up to five pale green flowers {{convert|12-15|mm|in|sigfig=1|abbr=on}} long and {{convert|10-12|mm|in|sigfig=1|abbr=on}} wide are borne on a thin, wiry flowering stem {{convert|200-400|mm|in|sigfig=1|abbr=on}} tall. The dorsal sepal is {{convert|5-6|mm|in|sigfig=2|abbr=on}} long and {{convert|3-4|mm|in|sigfig=1|abbr=on}} wide. The lateral sepals are {{convert|6-7|mm|in|sigfig=1|abbr=on}} long and about {{convert|4|mm|in|sigfig=1|abbr=on}} wide. The petals are {{convert|5-6|mm|in|sigfig=2|abbr=on}} long and {{convert|1.5-2.5|mm|in|sigfig=1|abbr=on}} wide. The labellum is flat, pale green and red, {{convert|12-13|mm|in|sigfig=2|abbr=on}} long and {{convert|3.5-5.5|mm|in|sigfig=1|abbr=on}} wide with bluish red hairs up to {{convert|2|mm|in|sigfig=1|abbr=on}} covering about three quarters of the labellum. The column lacks the sham "eyes" of some other beard orchids. Flowering occurs from December to February but each flower only lasts a few hours.{{cite book|last1=Jones|first1=David L.|title=A complete guide to native orchids of Australia including the island territories|date=2006|publisher=New Holland|location=Frenchs Forest, N.S.W.|isbn=1877069124|page =264}}
Taxonomy and naming
Calochilus caesius was first formally described in 2004 by David Jones and the description was published in The Orchadian from specimens collected at Yarrawonga Swamp near Darwin.{{cite web|title=Calochilus caesius|url= https://id.biodiversity.org.au/instance/apni/589443|publisher=APNI|accessdate=28 June 2018}} The specific epithet (caesius) is a Latin word meaning "bluish gray".{{cite book|last1=Brown|first1=Roland Wilbur|title=The Composition of Scientific Words|date=1956|publisher=Smithsonian Institution Press|location=Washington, D.C.|page=145}}
Distribution and habitat
The blue beard orchid grows in swampy places with rushes and sedges in the far north of the Northern Territory including Garig Gunak Barlu National Park, Kakadu National Park and Melville Island.