Microtis (plant)

{{Short description|Genus of orchids}} {{for|the mollusc genus|Microtis (gastropod)}} {{italic title}} {{Automatic taxobox | name = Onion orchids | image = Microtis parviflora (5286199239).jpg | image_caption = ''[[Microtis parviflora]]'' growing on [[Black Mountain (Australian Capital Territory)|Black Mountain]] in the [[Australian Capital Territory|A.C.T.]] | taxon = Microtis (plant) | authority = [[Robert Brown (botanist, born 1773)|R.Br.]]<ref name="APC">{{cite web |title=''Microtis'' |url=https://biodiversity.org.au/nsl/services/apc-format/display/73781|publisher=Australian Plant Census |access-date=20 October 2025}}</ref> | display_parents = 2 | synonyms_ref = <ref name="APC" /> | synonyms = * ''Goadbyella'' [[R.S.Rogers]] * ''Hydrorchis'' [[D.L.Jones]] & [[M.A.Clem.]] * ''Microtidium'' D.L.Jones & M.A.Clem }}

'''''Microtis''''', commonly known as '''onion orchids''' or '''mignonette orchids''' is a [[genus]] of about 20 [[species]] of [[plant]]s in the orchid [[Family (taxonomy)|family]], [[Orchidaceae]]. Onion orchids are [[Terrestrial plant|terrestrial]] [[Herbaceous plant|herbs]] with a single leaf at the base of the plant. They are similar to orchids in the genus ''[[Prasophyllum]]'' in that they have an onion-like leaf. The flowers are small but often scented and attractive to their insect pollinators. They are widespread in [[Asia]], [[Australia]] and some [[Pacific]] islands.[[File:Microtis media (labelled).001.jpg|thumb|225px|''Microtis media'' subsp. ''media'' labelled close up image]]

== Description == Orchids in the genus ''Microtis'' are terrestrial, [[Perennial plant|perennial]], [[deciduous]], [[sympodial]] herbs with a few inconspicuous, fine roots and an egg-shaped to almost spherical [[tuber]]. The tuber often produces two tubers on the end of long, root-like [[stolon]]s. There is a single, linear, cylindrical, onion-like leaf at the base of the plant. The leaf resembles that of the closely related genus ''[[Prasophyllum]]'' except that is entirely green (usually red at the base in ''Prasophyllum'') and exudes clear [[wikt:mucilage|mucilage]] when damaged.<ref name="Hoffman">{{cite book|last1=Hoffman|first1=Noel|last2=Brown|first2=Andrew|title=Orchids of South-West Australia.|date=2011|publisher=Noel Hoffman|location=Gooseberry Hill|isbn=9780646562322|pages=333–349|edition=3rd}}</ref><ref name="Bates">{{cite journal|last1=Bates|first1=Robert J.|title=The genus ''Microtis'' R.Br. (Orchidaceae): A taxonomic revision with notes on biology|journal=Journal of the Adelaide Botanic Garden|date=1984|volume=7|issue=1|pages=45–89}}</ref><ref name="Orchids">{{cite book|editor-last1=Pridgeon |editor-first1=Alec M.|editor-last2=Cribb |editor-first2=Phillip J.|editor-last3=Chase |editor-first3=Mark W.|editor-last4=Rasmussen |editor-first4=Finn|title=Genera Orchidacearum, Volume 2, Orchidoideae (part 1)|date=2001|publisher=Oxford University Press|location=Oxford, England|isbn=0198507100|pages=181–186}}</ref><ref name="RBGS">{{cite web|last1=Rowe|first1=Ross|title=Genus ''Microtis''|url=http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&showsyn=&dist=&constat=&lvl=gn&name=Microtis|publisher=Royal Botanic Gardens Sydney: plantnet|accessdate=9 July 2016}}</ref><ref name="Vicflora">{{cite web|title=''Microtis''|url=http://data.rbg.vic.gov.au/vicflora/flora/taxon/92e9fdc4-ae26-4508-821d-d31dd4243af0|publisher=Royal Botanic Gardens Victoria:Vicflora|accessdate=9 July 2016}}</ref><ref name="efloraSA">{{cite web|title=''Microtis''|url=http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&family=&genus=Microtis&species=&iname=&submit=Display|publisher=State Herbarium of South Australia:efloraSA|accessdate=9 July 2016}}</ref>

The [[inflorescence]] is a [[raceme]] with a few to many [[Resupination#Orchidaceae|resupinate]] green [[flower]]s spirally arranged on a flowering stem. Each flower has a short stalk with a small [[bract]] near its base. The broad [[wikt:dorsal|dorsal]] [[sepal]] is sharp-pointed, dished on the lower side and forms a horizontal hood over the [[Column (botany)|column]]. The [[wikt:lateral|lateral]] sepals are similar to, but much narrower than the dorsal sepal. The [[petal]]s are smaller than the sepals, thin and are spread below or under the dorsal sepal. As is usual in orchids, one petal is highly modified as the central labellum. The labellum is egg-shaped to oblong and hangs or is curved against the ovary. The sexual parts of the flower are fused to the [[Column (botany)|column]], which is shaped like half a cylinder. Flowering time depends on the climatic region where the species is found and the fruit that follows flowering is a non-fleshy, [[Dehiscence (botany)|dehiscent]] [[Capsule (botany)|capsule]] containing up to 500 seeds.<ref name="Hoffman" /><ref name="Bates" /><ref name="RBGS" /><ref name="Vicflora" /><ref name=FloraBase>{{FloraBase|name=''Microtis''|id=21287}}</ref>

==Taxonomy and naming== The genus ''Microtis'' was first formally described by [[Robert Brown (Scottish botanist from Montrose)|Robert Brown]] in 1810 and the description was published in ''[[Prodromus Florae Novae Hollandiae]]''.<ref name=APNI>{{cite web|title=''Microtis''|url= http://id.biodiversity.org.au/instance/apni/486057|publisher=APNI|accessdate= 9 July 2016}}</ref> Brown described five species at the time (''[[Microtis parviflora|M. parviflora]]'', ''[[Microtis rara|M. rara]]'', ''[[Microtis media|M. media]]'', ''[[Microtis alba|M. alba]]'' and ''[[Microtis pulchella|M. pulchella]]'') but did not nominate a [[type species]].<ref name="Brown">{{cite book|last1=Brown|first1=Robert|title=Prodromus Florae Novae Hollandiae (Vol. 1)|date=1810|location=London|page=320|url=https://www.biodiversitylibrary.org/item/21771#page/190/mode/1up|accessdate=9 July 2016}}</ref> The name ''Microtis'' is derived from the [[ancient Greek]] words ''mikros'' (μικρός) meaning "small" and ''ous'', genitive ''ōtos'' (οὖς, genitive ὠτός) meaning "ear",<ref name="Backer">Backer, C.A. (1936). ''Verklarend woordenboek der wetenschappelijke namen van de in Nederland en Nederlandsch-Indië in het wild groeiende en in tuinen en parken gekweekte varens en hoogere planten'' (Edition Nicoline van der Sijs).</ref> referring to the small, ear-like appendages on the column.<ref name="Bates" />

==Distribution and habitat== Onion orchids are widespread in temperate areas of Australia and in sub-tropical [[Queensland]], occurring in all states but not the [[Northern Territory]]. ''[[Microtis parviflora]]'' and ''[[Microtis unifolia|M. unifolia]]'' are the most widely distributed species and also occur on both main islands of [[New Zealand]] and as far south as [[Stewart Island|Stewart]] and possibly [[Auckland Island|Auckland]] Islands as well as [[New Caledonia]], and [[Norfolk Island|Norfolk]], [[Lord Howe Island|Lord Howe]] and the [[Kermadec Islands]] in the [[Pacific Ocean|western Pacific]]. These two species are also found in [[Malaysia]], [[Indonesia]], the [[Philippines]], [[Taiwan]], southern [[Japan]], the [[Ryukyu Islands]] and possibly on the [[China|Chinese]] mainland. They usually grow in areas that are wet in winter or in areas of high rainfall.<ref name="Bates" />

==Ecology== ===Disease=== The leaves of onion orchids are susceptible to fungal disease and most leaves appear to have some damage. The rust ''[[Uromyces microtidis]]'' has been identified as a [[pathogen]].<ref name="Bates" />

===Pollination=== ''Microtis'' flowers are insect pollinated. For some species, the insect is a small wasp from a species of [[Ichneumonidae]] or [[Braconidae]]. ''Microtis'' are rarely pollinated by ants because the mouthparts of ants usually have antibiotic secretions which damage pollen grains. However, several species of ''Microtis'', including ''M. parviflora'' are pollinated by wingless worker ants from the genera ''[[Iridomyrmex]]'' (Family [[Dolichoderinae]]), ''[[Meranops]]'' (Family [[Myrmeciinae]]) and ''[[Rhytidoponera]]'' (Family [[Ponerinae]]), having been attracted by nectar secreted from the base of the labellum.<ref name="Orchids" /><ref name="Abrol">{{cite book|last1=Abrol|first1=Dharam P.|title=Pollination biology : biodiversity conservation and agricultural production|url=https://archive.org/details/pollinationbiolo00abro|url-access=limited|date=2010|publisher=Springer|location=Dordrecht|isbn=9789400719415|page=[https://archive.org/details/pollinationbiolo00abro/page/n318 288]}}</ref>

===Autogamy=== [[Reproduction#Autogamy|Autogamy]] has been observed in several species of onion orchid. In some cases, the pollen grains fall onto the stigma and germinate but in others, including in some populations of ''M. parvifolia'', if the flowers have not been cross-pollinated, the stigma grows upwards until it contacts the [[Pollinium|pollinia]], so that seed is always produced.<ref name="Orchids" />

== Species == The taxonomy of ''Microtis'' has been confused ever since Robert Brown first described the genus. He did not include ''Ophrys unifolia'' [[Georg Forster|G.Forst.]] (1786)<ref name=APNI(1)>{{cite web|title=''Ophrys unifolia''|url= http://id.biodiversity.org.au/instance/apni/567976|publisher=APNI|accessdate= 9 July 2016}}</ref> and ''Epipactis porrifolia'' [[Sw.]] (1800)<ref name=APNI(2)>{{cite web|title=''Epipactis porrifolia''|url= http://id.biodiversity.org.au/instance/apni/537050|publisher=APNI|accessdate= 9 July 2016}}</ref> and these names were used by later authors, although now recognised as ''Microtis media''. The small size of the flowers and their tendency to change when dried as herbarium species led to further confusion.<ref name="Bates" />

{{div col|colwidth=35em}} * ''[[Microtis alba]]'' R.Br. (1810) – white mignonette orchid ([[Southwest Australia|SW]] Australia) * ''[[Microtis alboviridis]]'' R.J.Bates (2008) – scented mignonette orchid (SW Australia) * ''[[Microtis angusii]]'' D.L.Jones (1996) – Mona Vale onion orchid (New South Wales) * ''[[Microtis arenaria]]'' Lindl. (1840) – notched onion orchid (south-east Australia) * ''[[Microtis atrata]]'' Lindl. (1840) – swamp mignonette orchid (southern Australia) * ''[[Microtis brownii]]'' Rchb.f. (1871) – sweet mignonette orchid (SW Australia) * ''[[Microtis cupularis]]'' (D.L.Jones & G.Brockman) A.P.Br. (2005) – cupped mignonette orchid (SW Australia) * ''[[Microtis eremaea]]'' R.J.Bates (1996) – slender mignonette orchid (SW Australia) * ''[[Microtis eremicola]]'' (R.J.Bates) D.L.Jones & M.A.Clem. (1996) – desert mignonette orchid (SW Australia) * ''[[Microtis familiaris]]'' R.J.Bates (1990) – coastal mignonette orchid (SW Australia) * ''[[Microtis globula]]'' R.J.Bates (1984) – globular mignonette orchid (SW Australia) * ''[[Microtis gracilenta]]'' R.J.Bates (2015) (South Australia) * ''[[Microtis graniticola]]'' R.J.Bates, (1984) – globular mignonette orchid (SW Australia) * ''[[Microtis media]]'' R.Br. (1810) (SW Australia) ** [[Microtis media subsp. densiflora|''Microtis media'' subsp. ''densiflora'']] (Benth.) R.J.Bates, (1990) – dense mignonette orchid (SW Australia) ** [[Microtis media subsp. media|''Microtis media'' subsp. R.Br. ''media'']] – common mignonette orchid (SW Australia) * ''[[Microtis oblonga]]'' R.S.Rogers (1923) – sweet onion orchid (SE Australia) * ''[[Microtis oligantha]]'' L.B.Moore, (1968) – small onion orchid (New Zealand) * ''[[Microtis orbicularis]]'' R.S.Rogers (1907) – dark mignonette orchid (southern Australia) * ''[[Microtis parviflora]]'' R.Br. (1810) – slender onion orchid (all Australian states) * ''[[Microtis pulchella]]'' R.Br. (1810) – beautiful mignonette orchid (SW Australia) * ''[[Microtis quadrata]]'' (R.J.Bates) D.L.Jones & M.A.Clem. (1996) – south coast mignonette orchid (SW Australia) * ''[[Microtis rara]]'' R.Br., Prodr. (1810) – scented onion orchid (all Australian states) * ''[[Microtis unifolia]]'' (G.Forst.) Rchb.f. (1871) – common onion orchid (widespread from China, Japan, Philippines, Indonesia, Australia, New Zealand) {{div col end}}

== Use in horticulture == Most ''Microtis'' are very easy to grow, and readily volunteer themselves in other pots. Onion orchids are often found in gardens around [[Melbourne]] from wind-born seed.<ref name="Orchids" />

===Gallery=== <gallery> Image:Microtis media.jpg|[[Franz Bauer]]'s 1835 illustration of ''[[Microtis media]]'' from ''[[Curtis's Botanical Magazine]]'' Image:Microtis parviflora - Flickr 003.jpg|''[[Microtis parviflora]]'' (habit) Image:Microtis unifolia nirabarn01.JPG|''[[Microtis unifolia]]'', [[Tanabe, Wakayama]], Japan Image:Microtis unfolia nirabarn00.JPG|''[[Microtis unifolia|M. unifolia]]'' known as Nirabaran in Japan </gallery>

== References == {{Reflist}} * {{cite journal | author = Jones D.L. | title = ''Microtis angusii, a new species of Orchidaceae from Australia'' | journal = The Orchadian | volume = 12 | issue = 1 | pages = 10–12 | year = 1996}} * {{cite journal | author = R. Peakall, A. J. Beattie | title = ''Pollination of the Orchid Microtis parviflora'' R. Br. by Flightless Worker Ants | journal = Functional Ecology | volume = 3 | issue = 5 | year = 1989 |pages = 515–522 | doi = 10.2307/2389565 | publisher = British Ecological Society | jstor = 2389565}}

== External links == * {{Commons-inline|italic=1}} * [http://www.anos.org.au/groups/newzealand/journals/nzoj-67.htm New Zealand Native orchid group]

[[Category:Microtis (plant)| ]] [[Category:Diurideae genera]]