Description: Annual or perennial herbs, glandular, aromatic.
Leaves cauline, alternate, margins usually toothed, sessile.
Heads lateral or in terminal racemes, ± sessile, solitary; involucral bracts 2-seriate, imbricate, herbaceous with scarious margins; receptacle convex, pitted, naked. Outer florets tubular, female, multiseriate; corollas minute, conical, apex narrowed, 2 or 3 small lobes; style branches linear, acute, glabrous. Inner florets ± campanulate, bisexual, fertile, 4-toothed; style branches oblong, truncate, apices papillose. Anthers obtuse at base, apical appendages ovate.
Achenes clavate to cylindrical; ribs 3–5, obtuse, pubescent; pappus absent.
Distribution and occurrence: World: c. 12 species, Asia, South America, New Zealand, Australia. Australia: c. 11 species, all States.
Text by E. A. Brown; key updated Feb 2016 Louisa Murray
Taxon concept: Walsh, N.G.(2001) Revision of Centipeda. Muelleria Vol 15 ; 33-64; key adapted from Adapted from http://keybase.rbg.vic.gov.au/keys/show/2692
| ||Key to the species|| |
|1||Achenes ± narrowly obovate in outline, usually somewhat flattened, rounded to obtuse at apex, the ribs not terminating in a thickened, spongy or corky apical portion; plants creeping, often rooting at lower nodes, wholly glabrous or with short arachnoid hairs near the growing tip; capitula distinctly (but shortly) pedunculate||Centipeda elatinoides |
|Achenes linear or narrowly obcuneate in outline, ± isodiametric, truncate or nearly so at apex, the ribs terminating in a somewhat thickened, spongy or corky apical portion; plants erect to prostrate, but not or rarely rooting at lower nodes, subglabrous to distinctly hairy; capitula often sessile||2|
|2||Achenes up to 1.1 mm long (rarely to 1.3 mm and if so then capitula in short racemose axillary inflorescences); capitula solitary or in short racemes||3|
|Achenes longer than 1.1 mm; flower heads always solitary|
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|3||Achenes broadly cuneiform, ± half as wide as long, prominently 4- or 5-angled, often narrowly winged at the angles, the intervening faces concave; plants usually distinctly cottony||Centipeda nidiformis |
|Achenes at least 3 times as long as wide, ribbed but not winged, with intervening faces flat or convex; plants glabrescent to cottony|
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|4||Inflorescence a single terminal, axillary or leaf-opposed flower heads||6|
|Inflorescence (sometimes very shortly) racemose, of 2–7 flower heads (rarely the lowermost inflorescences a single capitulum)|
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|5||Perennial (but dying down annually to penetrating rootstock; inforescences terninal (sometimes also in upper axils) 0.5–2 cm long, 2–7 flowerheads, heads sub-globular||Centipeda racemosa|
|Short lived annual; inflorescences axillary, to 0,5 cm long, 2–4 flowerheads, heads hemispherical to biconvex|
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|6||Fruiting heads firm, not readily breaking up, fruiting involucre bowl- or cup-shaped; receptacle more or less flat to slightly domed; achenes with pericarp thickish, often obscuring the brown testa of the underlying seed||Centipeda crateriformis |
|Fruiting heads soft, readily disintegrating, involucre bracts at fruiting widely spreading or reflexed; receptacle distinctly convex; achenea with pericarp thin between ribs, the brown testa of the underlying seed clearly apparent|
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|7||Fruiting involucre cup-shaped to campanulate; achenes with hairs confined to a basal ring and a subapical band; plants strictly annual, usually erect||Centipeda thespidioides |
|Fruiting involucre bowl-shaped, or involucral bracts widely spreading or deflexed; cypselas with hairs scattered along ribs (and sometimes on faces); plants annual or perennial|
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|8||Receptacle prominently raised (± hemispherical); involucral bracts at fruiting widely spreading or deflexed||Centipeda cunninghamii |
|Receptacle slightly concave to slightly convex; fruiting involucre ± bowl-shaped|
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