Biology:Olearia

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Short description: Genus of flowering plants

Olearia
Olearia stuartii.jpg
Olearia stuartii in Geelong Botanic Gardens
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Asteroideae
Tribe: Astereae
Subtribe: Brachyscominae
Genus: Olearia
Moench[1]
Type species
Olearia tomentosa
(J.C.Wendl.) DC.[1]
Species

See text

Olearia, most commonly known as daisy-bush,[2] is a genus of flowering plants belonging to the family Asteraceae, the largest of the flowering plant families in the world. Olearia are found in Australia, New Guinea and New Zealand. The genus includes herbaceous plants, shrubs and small trees. The latter are unusual among the Asteraceae and are called tree daisies in New Zealand. All bear the familiar daisy-like composite flowerheads in white, pink, mauve or purple.

Description

Plants in the genus Olearia are shrubs of varying sizes, characterised by a composite flower head arrangement with single-row ray florets enclosed by small overlapping bracts arranged in rows. The flower petals are more or less equal in length. The centre of the bi-sexual floret is disc shaped and may be white, yellowish or purplish, generally with 5 lobes. Flower heads may be single or clusters in leaf axils or at the apex of branchlets. Leaves may be smooth, glandular or with a sticky secretion. The leaves may grow opposite, alternate, arranged sparsely or clustered. Leaf margins either entire or lobed, with or without a stalk. The fruit are dry slightly compressed, one-seeded, narrow-elliptic or egg-shaped with longitudinal ridges and smooth or with sparse hairs.[3][4][5]

Taxonomy and naming

The genus Olearia was first described in 1802 by Conrad Moench in Supplementum ad Methodum Plantas and is named after Johann Gottfried Olearius, a 17th-century German scholar and author of Specimen Florae Hallensis.[6][7] Originally a large genus, a molecular study has found it to be polyphyletic.[8]

Distribution

There are approximately 180 species of Olearia, of which about 112 species are endemic to Australia. Olearia are found in all states of Australia.[5]

Species

Olearia archeri
Olearia cordata
Olearia erubescens
Olearia minor
Olearia oporina
Olearia suffruticosa
Olearia tomentosa

The following is a list of Olearia species accepted by the Australian Plant Census or the New Zealand Plant Conservation Network or listed in the Census of Vascular Plants of Papua New Guinea as at May 2021:[9][10][11]


Use in horticulture

Several species are cultivated as ornamental garden plants, and there are hybrids of uncertain or mixed parentage. Among these, the following have been given the Royal Horticultural Society’s Award of Garden Merit:-[12]

  • Olearia macrodonta, New Zealand holly[13]
  • Olearia × mollis ‘Zennorensis’, daisy bush ‘Zennorensis’[14]
  • Olearia × scilloniensis[15]
  • Olearia × scilloniensis ‘Master Michael’[16]

They are generally hardy down to −10 °C (14 °F), but require a sheltered spot in full sun.

References

  1. 1.0 1.1 "Olearia Moench". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government. http://www.anbg.gov.au/cgi-bin/apni?taxon_id=49388. 
  2. "Olearia". Australian National Botanic Gardens. http://www.anbg.gov.au/common.names/. 
  3. "Olearia". Royal Botanic Gardens Victoria. https://vicflora.rbg.vic.gov.au/flora/taxon/b2e719d2-67b1-4a97-bdd1-32498cdf749b. 
  4. Holliday, Ivan. "Olearia". http://anpsa.org.au/APOL35/sep04-4.html. 
  5. 5.0 5.1 Lander, N.S.. "Olearia". New South Wales Flora Online. http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&showsyn=&dist=&constat=&lvl=gn&name=Olearia. 
  6. "Olearia". APNI. https://id.biodiversity.org.au/instance/apni/559552. 
  7. de Lange, Peter J.. "Olearia adenocarpa". New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/olearia-adenocarpa/. 
  8. Cross, E.W.; Quinn, C.J.; Wagstaff, S.J. (2002). "Molecular evidence for the polyphyly of Olearia (Astereae: Asteraceae)". Plant Systematics and Evolution 235 (1–4): 99–120. doi:10.1007/s00606-002-0198-9. 
  9. "Olearia". Australian Plant Census. https://biodiversity.org.au/nsl/services/search?product=APC&tree.id=51209179&name=Olearia&inc._scientific=&inc.scientific=on&inc._cultivar=&max=1000&display=apc&search=true. 
  10. "Olearia". New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/?quick_search=Olearia. 
  11. Conn, Barry J.. "Census of the Vascular Plants of Papua New Guinea". Royal Botanic Garden Sydney. http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/PNGcensus.pl?fam=&gen=Olearia&sp=&infr=&group=. 
  12. "AGM Plants – Ornamental". Royal Horticultural Society. July 2017. p. 69. https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf. 
  13. "RHS Plantfinder – Olearia macrodonta". https://www.rhs.org.uk/Plants/11760/i-Olearia-macrodonta-i/Details. 
  14. "RHS Plantfinder – Olearia × mollis ‘Zennorensis’". https://www.rhs.org.uk/Plants/76193/i-Olearia-i-×-i-mollis-i-Zennorensis/Details. 
  15. "Olearia × scilloniensis". RHS. https://www.rhs.org.uk/Plants/119765/Olearia-x-scilloniensis-Dorrien-Smith/Details. 
  16. "RHS Plantfinder – Olearia × scilloniensis ‘Master Michael’". https://www.rhs.org.uk/Plants/44008/i-Olearia-i-×-i-scilloniensis-i-Master-Michael/Details. 

Wikidata ☰ Q291873 entry