Acianthus fornicatus

Acianthus fornicatus is a terrestrial, perennial, deciduous, sympodial herb with a single heart-shaped, glabrous, dark green leaf which is reddish-purple on its lower surface. The leaf is {{convert|10-40|mm|in|sigfig=1|abbr=on}} long, {{convert|10-20|mm|in|sigfig=1|abbr=on}} wide on a stalk {{convert|4-9|cm|in|sigfig=1|abbr=on}} high.{{cite web|last1=Jones|first1=David L.|title=Acianthus fornicatus|url=http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acianthus~fornicatus|publisher=Royal Botanic Gardens Sydney:plantnet|access-date=18 June 2016}}{{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=1-877069-12-4|page=162}}

There are up to ten flowers, well-spaced on a raceme {{convert|100-300|mm|in|sigfig=1|abbr=on}} tall, each flower {{convert|10-40|mm|in|sigfig=1|abbr=on}} long and translucent, pinkish-red with a green, sometimes blackish labellum. The dorsal sepal is broadly egg-shaped, {{convert|9-12|mm|in|sigfig=1|abbr=on}} long, {{convert|5-6|mm|in|sigfig=2|abbr=on}} wide and forms a hood over the column. The lateral sepals are {{convert|9-12|mm|in|sigfig=1|abbr=on}} long, {{convert|1.4|mm|in|sigfig=1|abbr=on}} long wide with tips {{convert|2-4|mm|in|sigfig=1|abbr=on}} long and may be crossed or parallel to each other. The petals are about {{convert|4 x 1|mm|in|sigfig=1|abbr=on}} long and spread widely. The labellum is green, rarely blackish, egg-shaped to lance-shaped, with the outer edges turned under. When flattened, it is heart-shaped, {{convert|5-6|mm|in|sigfig=2|abbr=on}} long, {{convert|2.5-3|mm|in|sigfig=2|abbr=on}}. There is a thick, fleshy callus covering most of the central area and many small pimple-like papillae on the outer half. Flowering occurs between May and August.

This species is distinguished from others in the genus by its largish, projecting flowers, usually pinkish colouring, and broad dorsal sepal and labellum.

Acianthus fornicatus was first formally described by Robert Brown in 1810 and the description was published in Prodromus florae Novae Hollandiae.{{cite web|title=Acianthus fornicatus|url=https://id.biodiversity.org.au/instance/apni/485195|publisher=APNI|access-date=16 September 2019}}{{cite book|last1=Brown|first1=Robert|title=Prodromus Florae Novae Hollandiae|date=1810|location=London|page=321|url=https://www.biodiversitylibrary.org/item/21871#page/189/mode/1up|access-date=18 June 2016}} The specific epithet (fornicatus) is a Latin word meaning "vaulted" or "arched".{{cite web|last1=Lewis|first1=Charlton T.|last2=Short|first2=Charles|title=fornicatus|url=https://www.perseus.tufts.edu/hopper/text?doc=fornicatus&fromdoc=Perseus%3Atext%3A1999.04.0059|publisher=A Latin Dictionary|access-date=18 June 2016}}

This mosquito orchid is widespread and common in coastal and near-coastal areas in heathy forest and coastal scrub, growing in well-drained sandy loam. It occurs in Queensland and in New South Wales as far south as Eden.

Acianthus fornicatus is not threatened in New South Wales, but is classified as threatened in Victoria, where it is found only on Gabo Island.[https://vicflora.rbg.vic.gov.au/flora/taxon/71c3509d-7631-47d3-939f-1a5e17638354 VicFlora: Acianthus fornicatus]

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fornicatus

Category:Orchids of New South Wales

Category:Orchids of Queensland

Category:Endemic orchids of Australia

Category:Plants described in 1810

Category:Taxa named by Robert Brown (botanist, born 1773)