Cotula australis

{{Short description|Species of flowering plant}}

{{Redirect |Annual buttonweed |the moth with this name |Datana robusta{{!}}Datana robusta}}

{{Use dmy dates|date=July 2019}}

{{Speciesbox

|image = Cotula australis.jpg

|genus = Cotula

|species = australis

|authority = (Sieber ex Spreng.) Hook.

|synonyms_ref = [http://www.theplantlist.org/tpl1.1/record/gcc-130452 The Plant List, Cotula australis (Sieber ex Spreng.) Hook.f. ]

|synonyms =

• Anacyclus australis Sieber ex Spreng.
• Cotula venosa Colenso
• Lancisia australis (Sieber ex Spreng.) Rydb.
• Soliva tenella A.Cunn.
• Strongylosperma australe (Sieber ex Spreng.) Less.

}}

Cotula australis is a species of plant in the daisy family known by the common names bachelor's buttons, annual buttonweed,{{BSBI 2007 |access-date=2014-10-17}} southern waterbuttons and Australian waterbuttons. This small plant is native to Australia and New Zealand, but it is known in other areas of the world as a common weed (South America, California, Mexico, South Africa, etc.).{{Cite web |url=http://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:apni.taxon:308635 |title=Atlas of Living Australia, Cotula australis (Sieber ex Spreng.) Hook.f., Bachelor's Buttons |access-date=11 June 2015 |archive-url=https://web.archive.org/web/20160304103525/http://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:apni.taxon:308635 |archive-date=4 March 2016 |url-status=dead }}[https://www.biodiversitylibrary.org/item/54141#page/179/mode/1up Hooker, Joseph Dalton 1853. Botany of the Antarctic voyage of H.M. discovery ships Erebus and Terror in the Years 1839-1843 :under the command of Captain Sir James Clark Ross, part 2, Flora Novae-Zelandiae 1: 128][http://bonap.net/MapGallery/County/Cotula%20australis.png Biota of North America Program 2014 county distribution map]Jørgensen, P. M. & C. Ulloa Ulloa. 1994. Seed plants of the high Andes of Ecuador—A checklist. AAU Rep. 34: 1–443Gibbs Russell, G. E., W. G. M. Welman, E. Retief, K. L. Immelman, G. Germishuizen, B. J. Pienaar, M. Van Wyk & A. Nicholas. 1987. List of species of southern African plants. Memoirs of the Botanical Survey of South Africa 2(1–2): 1–152(pt. 1), 1–270(pt. 2).Turner, B. L. 1996. The Comps of Mexico: A systematic account of the family Asteraceae, vol. 6. Tageteae and Athemideae. Phytologia Memoirs 10: i–ii, 1–22, 43–93

Cotula australis grows low to the ground in a thin mat with some slightly erect, spindly stems. The leaves are divided and subdivided into fringelike lobes. The plant flowers in inflorescences only a few millimetres wide containing minuscule yellow disc florets surrounded by greenish brown bracts and rudimentary ray florets that have been reduced to pistils with no stamens or corolla. The fruit is a tiny winged achene about a millimetre wide.[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242426659 Flora of North America, Cotula australis (Sieber ex Sprengel) Hooker f.]