Arthrochilus rosulatus

Arthrochilus rosulatus is a terrestrial, perennial, deciduous, sympodial herb with an underground tuber that produces daughter tubers on the end of root-like stolons. It has a rosette of between three and four elliptic to lance-shaped leaves surrounding the base of the flowering stem, each leaf {{convert|10-35|mm|in|sigfig=1|abbr=on}} long and {{convert|8-12|mm|in|sigfig=1|abbr=on}} wide. Between two and fifteen pale green, insect-like flowers {{convert|8-13|mm|in|sigfig=1|abbr=on}} long are borne on a flowering stem {{convert|70-150|mm|in|sigfig=1|abbr=on}} tall. The dorsal sepal is linear to egg-shaped with the narrower end towards the base, {{convert|7.5-9|mm|in|sigfig=2|abbr=on}} long, about {{convert|2|mm|in|sigfig=1|abbr=on}} wide and partly wrapped around the base of the column. The lateral sepals are oblong to lance-shaped with the narrower end towards the base, {{convert|5.5-6.5|mm|in|sigfig=1|abbr=on}} long and about {{convert|2|mm|in|sigfig=1|abbr=on}} wide. The petals are linear, {{convert|6.5-7.5|mm|in|sigfig=2|abbr=on}} long and {{convert|1|mm|in|sigfig=1|abbr=on}} wide and curved. The lateral sepals and petals are turned back against the ovary. The labellum is light green with a dark purplish blotch at its base, about {{convert|5|mm|in|sigfig=1|abbr=on}} long, {{convert|1|mm|in|sigfig=1|abbr=on}} wide on a short stalk or "claw". There is an insect-like callus about {{convert|3.5|mm|in|sigfig=1|abbr=on}} long with short, reddish brown, hair-like glands in a central band. The tip of the callus is about {{convert|1.5|mm|in|sigfig=1|abbr=on}} wide with shiny dark reddish or black glands. The column is translucent with a few purplish spots, curved, and has two pairs of curved wings. Flowering occurs from November to July.{{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|pages =152–153}}{{cite journal|last1=Jones|first1=David L.|title=New taxa of Australian Orchidaceae|journal=Australian Orchid Research|date=1991|volume=2|pages=10–11}}{{cite web |author1=D.L.Jones |author2=T.Hopley |author3=S.M.Duffy |author1-link=David L. Jones (botanist) |year=2010 |access-date=31 May 2021 |url=http://www.canbr.gov.au/cpbr/cd-keys/RFKOrchids/key/rfkorchids/Media/Html/Arthrochilus_rosulatus.htm |title=Factsheet - Arthrochilus rosulatus |website=Australian Tropical Rainforest Orchids |publisher=Centre for Australian National Biodiversity Research (CANBR), Australian Government}}

Arthrochilus rosulatus was first formally described in 1991 by David Jones from a specimen collected near Rossville. The description was published in Australian Orchid Research.{{cite web|title=Arthrochilus rosulatus|url= https://id.biodiversity.org.au/instance/apni/551538|publisher=APNI|accessdate=30 April 2018}} The specific epithet (rosulatus) is a Latin word meaning "of roses",{{cite book|last1=Brown|first1=Roland Wilbur|title=The Composition of Scientific Words|date=1956|publisher=Smithsonian Institution Press|location=Washington, D.C.|page=667}} referring to the leaf rosette surrounding the base of the flowering stem, contrasting with others in the genus that have them on side growth.

The rosetted elbow orchid grows in forest in the vicinity of Cooktown, sometimes forming spreading colonies.

As with other Arthrochilus orchids, A. rosulatus is pollinated by male thynnid wasps of the genus Arthrothynnus although the species involved is not known. It also reproduces asexually by producing new tubers.{{cite web|title=Arthrochilus|url=https://www.anbg.gov.au/cpbr/cd-keys/orchidkey/html/genera/Arthrochilus.htm|publisher=Australian National Botanic Garden|accessdate=26 April 2018}}

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rosulatus

Category:Plants described in 1991

Category:Orchids of New South Wales

Category:Orchids of Queensland