Sp. Pl. 2: 891. 1753
Gen. Pl. ed. 5, 380. 1754
Annuals or perennials, 2–25[–50+] cm (sometimes aromatic). Stems usually 1, erect or prostrate to decumbent or ascending (sometimes rooting at nodes), usually branched, glabrous or ± strigillose to villous (hairs mostly basifixed). Leaves usually mostly cauline [basal]; alternate [opposite]; petiolate or sessile; blades obovate or spatulate to lanceolate or linear, sometimes 1–3-pinnately [palmati-pinnately] lobed, ultimate margins entire or irregularly toothed, faces glabrous or ± strigillose to villous [lanate] (hairs mostly basifixed). Heads disciform [discoid or radiate], borne singly (peduncles sometimes dilated). Involucres broadly hemispheric to saucer-shaped, 3–12+[–15+] mm diam. Phyllaries persistent, 13–30+ in 2–3+ series, margins and apices (colorless, light to dark brown, or purplish) scarious. Receptacles flat to convex [conic], epaleate (sometimes ± covered with persistent stalks of florets). Ray florets 0 [5–8+, pistillate, fertile; corollas white] (peripheral pistillate florets 8–80+ in 1–3+ series; corollas usually none). Disc florets 12–200+[–600+], bisexual, fertile [functionally staminate]; corollas ochroleucous or yellow, tubes ± cylindric (bases sometimes adaxially saccate), throats abruptly ampliate, lobes (3–)4, ± deltate (sometimes one larger than others, usually each with central resin canal). Cypselae obovoid to oblong, ob-compressed or -flattened, ribs 2, lateral, sometimes becoming wings, faces ± papillate (pericarps relatively thin, sometimes with myxogenic cells and/or 2 lateral resin sacs); pappi 0. x = 10.
Introduced; s Old World, introduced also (perhaps some native) in Mexico, South America, s Oceanic Islands.
Species 55 (2 in the flora).
Some species of Cotula are widely naturalized. F. Hrusa et al. (2002) reported Cotula mexicana (de Candolle) Cabrera as established on golf courses in California; it is similar to C. australis and differs in leaf blades mostly 1-pinnate, receptacles pilose, and disc florets functionally staminate.
|1||Annuals (± villous); leaf blades 2–3-pinnately lobed; involucres 3–4(–6) mm diam.; pistillate florets 8–40(–80+) in ± 1–3+ series||Cotula australis|
|1||Perennials (glabrous); leaf blades entire or irregularly toothed or lobed; involucres 6–9 (–12+) mm diam.; pistillate florets 12–40+ in 1 series||Cotula coronopifolia|