Print Fact SheetSonchus oleraceus

Taxonomy

Sonchus oleraceus L., Sp. Pl. 2: 794. 1753.

Common synonyms

Lactuca oleracea M.Gómez Anales Hist. Nat. 19: 268. 1890.

Common name

Common sowthistle, colewort, annual sowthistle, field sowthistle, hare's lettuce/thistle, milk thistle, small sowthistle, smooth sowthistle

Description

Propagule or dispersal unit is the fruit with pappus. Fertile part 2.2-3.2 mm long, 0.2-1.2 mm wide, in side view widest in upper part (obovoid), +/- straight, the upper (apical) end narrowing, in cross-section flattened, basal scar (carpopodium) inconspicuous and undifferentiated, central, beak (=thinner sterile stalk between seed and pappus) absent, wings absent, fruit surface light brown or straw, smooth (except at cellular level), wrinkled, rarely with round protrusions or bumps, with no hairs (glabrous), rarely papillae (small protuberances) (by misinterpretation), thickened margin absent, longitudinal ribs present, 6-8(-10), their surfaces bumpy or notched, with no hairs (glabrous) (by misinterpretation) or papillae (small protuberances).

Pappus type bristles / hairs, pappus elements all +/- similar, up to 4-8 mm long, in several rows, pappus elements numerous, persistent, the individual bristles rough / serrated (barbellate), rarely smooth (by misinterpretation), +/- equal width along length, white / translucent.

Notes: Sonchus oleraceus and Sonchus tenerrimus are difficult to differentiate from their fruits, but the former appears to have fewer (6-8 vs. 8 or more) and more clearly defined longitudinal ribs.

Ecology

Annual to biennial herb, fruit wind-dispersed. Especially temperate to subtropical areas, but with tolerance for a wide variety of habitats and substrates except where vegetation is too dense. Found especially in agricultural lands, rail- and roadsides, wastelands, and urban areas, but also in coastal areas and dunes, grasslands, riverbanks and wetlands.

Native range

Europe, northern Africa, western Asia.

Introduced range

Cosmopolitan.

Past interceptions (Australia): origins

Canada, United States, Colombia, Ecuador, Spain, United Kingdom, Netherlands, Belgium, Italy, Germany, Czech Republic, Slovakia, Kenya, UAE, Afghanistan, India, China, Korea, Japan, Thailand, Malaysia, Indonesia.

Other or unidentified species of the genus from United States, Colombia, Ecuador, Spain, United Kingdom, Belgium, France, Germany, Hungary, Kenya, China, Korea, Japan, Thailand, Malaysia.

Past interceptions (Australia): commodities

Agricultural machinery, containers, cut flowers, machinery and parts new and used, new tyres, new vehicles, seeds for sowing, timber box, timber dunnage, timber pallets, used vehicles.

Other or unidentified species of the genus from cut flowers, dried herbs (medicinal), fresh fruit, machinery and parts, new vehicles.