Olearia, most commonly known as daisy-bush, 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.
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. Originally a large genus, a molecular study has found it to be polyphyletic.
In 2020 Guy L. Nesom named ten new genera – Ephedrides, Eoglandula (later synonymised with the revived Spongotrichum), Landerolaria, Linealia, Muellerolaria, Neolaria, Phaseolaster, Vicinia, Walsholaria, and Wollemiaster – in which to place the 29 paraphyletic species previously in Olearia.
Distribution
As of March 2026 Plants of the World Online accepts 135 species of Olearia in Australia, New Guinea, and New Zealand. PlantNET accepts...
