Olearia ledifolia

Olearia ledifolia typically forms a compact, low lying and rigid shrub about {{cvt|0.5|m}} tall. The branches are numerous and densely packed with young growth covered in fine rust-coloured hairs. The lower sections of the branches may have raised scars from leaves that fall off after one or two years. The dark green leaves are tough and leathery, oblong, approximately {{cvt|12–14|mm}} long and arranged alternately along the stems. The upper surface of the leaf is usually glabrous, with the margins of the leaf rolled down and inwards. The lower leaf surface is covered in fine hairs that may appear rusty brown to silver.{{Cite book|last=Howells|first=Christine|url=https://www.worldcat.org/oclc/803605684|title=Tasmania's natural flora.|date=2012|isbn=978-0-909830-66-3|edition=Second|location=Hobart, Tasmania|oclc=803605684}}{{Cite book|author=Launceston Field Naturalists Club|editor-last1=Cameron |editor-first1=Mary | url=https://www.worldcat.org/oclc/222625500|title=A guide to flowers & plants of Tasmania|date=1999|publisher=New Holland|isbn=1-876334-35-5|edition=revised|location=Frenchs Forest, N.S.W.|oclc=222625500}}{{Cite book|last1=Kirkpatrick|first1=Jamie B.|last2=Dombrovskis|first2=Peter |last3=Davis|first3=Georgina |last4=Eberhard|first4=Jo |url=https://www.worldcat.org/oclc/37215997 |title=Alpine Tasmania : an illustrated guide to the flora and vegetation|date=1997|publisher=Oxford University Press|isbn=0-19-553753-X|location=Melbourne|oclc=37215997}}{{Cite web|title=Key to Tasmanian Dicots|url=https://www.utas.edu.au/dicotkey/dicotkey/AST/ast/sOlearia_ledifolia.htm|access-date=2021-03-15}}

The heads or daisy-like "flowers" contain numerous florets, with involucral bracts at the base. The heads are daisy-like in appearance with 10 – 12 white ray florets, the ligule approximately {{cvt|10|mm}} long, surrounding deep yellow disc florets. The heads are borne singly on short peduncles in the leaf axils near the tips of branches. The fruit is a shiny, glabrous achene with seed dispersal being assisted by dry, wind borne pappus. Flowering occurs in the southern hemisphere summer months of January and February.{{Cite web|title=Descriptions of Dicot families|url=https://www.utas.edu.au/docs/plant_science/field_botany/species/dicots/famdicot.html|access-date=2021-03-15|website=www.utas.edu.au}}{{cite book |last1=Bentham |first1=George |title=Flora Australiensis |volume=3 |date=1867 |publisher=Lovell Reeve & Co. |location=London |page=472 |url=https://www.biodiversitylibrary.org/item/55517#page/484/mode/1up |access-date=13 May 2022}}

This species was first formally described in 1836 by Augustin Pyramus de Candolle who gave it the name Eurybia ledifolia in his Prodromus Systematis Naturalis Regni Vegetabilis from specimens collected in rocky places on Mount Wellington by Allan Cunningham.{{cite web|title=Eurybia ledifolia|url=https://id.biodiversity.org.au/instance/apni/22992 |publisher=APNI|accessdate=13 May 2022}}{{cite book |last1=de Candolle |first1=Augustin Pyramus |title=Prodromus Systematis Naturalis Regni Vegetabilis |volume=5 |date=1836 |publisher=Sumptibus Sociorum Treuttel et Würtz |location=Paris |page=269 |url=https://www.biodiversitylibrary.org/item/7154#page/274/mode/1up |accessdate=14 April 2019}} In 1867, George Bentham changed the name to Olearia ledifolia in Flora Australiensis.{{cite web|title=Olearia ledifolia|url=https://id.biodiversity.org.au/instance/apni/534141 |publisher=APNI|accessdate=13 May 2022}} The specific epithet (ledifolia) is derived from the Greek 'ledos' (woollen cloth) and the Latin 'folium' (leaf), referring to the hairy under surface of the leaves.{{Cite book|last=Wapstra|first=Mark|title=Tasmanian plant names unravelled|publisher=Fullers Bookshop|year=2010|isbn=9780980472028|location=Launceston, Tas}}

Olearia ledifolia is endemic to the island state of Tasmania and has been recorded on King Island.{{Cite web|last=Herbaria|first=jurisdiction:Australian Government Departmental Consortium;corporateName:Council of Heads of Australasian|title=Partners|url=https://avh.ala.org.au/occurrences/search?taxa=olearia+ledifolia#tab_recordsView|access-date=2021-03-15|website=avh.ala.org.au|language=en-AU}} It is a common species in alpine heath, bolster heath, deciduous heath, fjaeldmark, alpine sedgeland and coniferous heath at altitudes above 1000m.{{Cite book|last1=Harris|first1=Stephen|last2=Kitchener|first2=Anne | url=https://www.worldcat.org/oclc/183151378|title=From Forest to Fjaeldmark : descriptions of Tasmania's vegetation|date=2005|publisher=Department of Primary Industries, Water and Environment|isbn=0-7246-6364-9|location=Hobart|oclc=183151378}} Its common name, the rock daisy bush, refers to its preference for sheltered rocky slopes and scree fields amongst mountain plateaus.

Olearia ledifolia may become a co-dominant species at higher altitudes where the growth of trees is limited by climatic factors. These environments are subject to snow and ice, low temperatures, strong winds and high UV levels.{{Cite book|last1=Reid|first1=James B. |url=https://www.worldcat.org/oclc/224722819 |title=Vegetation of Tasmania|date=2005|publisher=Australian Biological Resources Study|isbn=0-646-44512-X|location=[Canberra, A.C.T.]|oclc=224722819}} The primary threat to the plant communities where O. ledifolia grows is fire, with frequent burning greatly decreasing the likelihood of recovery and leading to species impoverishment. However, it is unclear what the response of O. ledifolia is to fire at the species level.{{Cite journal|last=Kirkpatrick|first=J. B.|last2=Dickinson|first2=K. J. M.|date=1984|title=The Impact of Fire on Tasmanian Alpine Vegetation and Soils|url=https://www.publish.csiro.au/bt/bt9840613|journal=Australian Journal of Botany|language=en|volume=32|issue=6|pages=613–629|doi=10.1071/bt9840613|issn=1444-9862}} Other threats include trampling, grazing pressures from livestock and climate change.{{Cite web|title=Alpine Vegetation {{!}} Department of Primary Industries, Parks, Water and Environment, Tasmania|url=https://dpipwe.tas.gov.au/conservation/conservation-on-private-land/bush-information-management/identify-your-bush-type/bush-that-is-treeless/alpine-vegetation#:~:text=The%20alpine%20vegetation%20of%20Tasmania,by%20grasses,%20herbs%20or%20sedges.|access-date=2021-03-15|website=dpipwe.tas.gov.au}}

Strongly revolute leaf margins are a frequently recorded xeromorphic adaptions for plants that are subject to water stress, especially when coupled with growths of hair like trichomes.{{Cite book|last1=Mooney|first1=Harold A.|url=https://www.worldcat.org/oclc/817706274|title=Response of plants to multiple stresses|date=1991|publisher=Academic Press|others=Harold A. Mooney|isbn=1-299-19283-1|location=San Diego|oclc=817706274}} The morphology of the leaf serves to increase the boundary layer between the stomata positioned on the underside of the leaf and the external desiccating environment, thus preventing water loss during gas exchange.{{Cite journal|last=Fahn|first=Abraham|date=1986-05-01|title=Structural and Functional Properties of Trichomes of Xeromorphic Leaves|url=https://academic.oup.com/aob/article/57/5/631/137966|journal=Annals of Botany|language=en|volume=57|issue=5|pages=631–637|doi=10.1093/oxfordjournals.aob.a087146|issn=0305-7364}} The classically thin skeletal soils of alpine Tasmania where O. ledifolia occurs have limited water holding capacity and are often subject to summer drought conditions.

Due to its growth habit and the leaf morphology, Olearia ledifolia bears strong superficial resemblance to Orites revoluta (a member of the Proteaceae family) when not bearing reproductive structures. Compounding possible misidentification, these species are regularly found growing in close association with each other. The two species can be separated by the lack of hairy leaves, proteaceous flowers and splitting follicles of O. revoluta.

Olearia ledifolia is rarely cultivated because of its restrictive habitat requirements. However, surface sowing of freshly collected seed that has been allowed to dry has yielded some success, with germination occurring in 2 – 5 weeks. It prefers well-drained, moist, acidic soil in full sun and is frost and wind tolerant. It has proven resistant to the soil-borne disease Phytophthora cinnamomi, but it is intolerant to phosphorus.

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ledifolia

Category:Asterales of Australia

Category:Endemic flora of Tasmania