Taxonomy

Sonchus asper (L.) Hill., Herb. Brit. [Hill] 1: 47. 1769.

Common synonyms

Sonchus oleraceus var. asper L. Sp. Pl. 2: 794. 1753.

Common name

Prickly sowthistle

Description

Propagule or dispersal unit is the fruit with pappus. Fertile part 2-3.2 mm long, 0.3-1.8 mm wide, in side view widest in upper part (obovoid), +/- straight, the upper (apical) end narrowing, in cross-section flattened, basal scar (carpopodium) pronounced and well-differentiated, central, beak (=thinner sterile stalk between seed and pappus) absent, wings absent (by misinterpretation) or wings present, 0.2-0.5 mm wide, fruit surface light brown or straw or dark brown, smooth (except at cellular level), with no hairs (glabrous) or papillae (small protuberances), thickened margin absent, rarely present (by misinterpretation), thick margin hairs rarely papillae (small protuberances) (by misinterpretation), longitudinal ribs present, 6-8, their surfaces smooth, with papillae (small protuberances).

Pappus type bristles / hairs, pappus elements all +/- similar, up to 5-9 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: The most distinctive of the Sonchus species included in this key because its fruits have a smooth as opposed to bumpy surface, and it regularly has three ribs on each side. These have been scored as six to eight in total, to allow the interpretation of the margins as two additional ribs.

Ecology

Annual herb, fruits wind-dispersed. Temperate to Mediterranean areas. Found on disturbed grasslands, gardens, rail- and roadsides, wasteland, agricultural areas.

Native range

 Europe, North Africa, temperate Asia.

Introduced range

Canada, United States, Mexico, South America, Namibia, South Africa, southern Asia, Taiwan, Japan, Australia, New Zealand.

Past interceptions (Australia): origins

Canada, United States, Ecuador, Netherlands, Germany, Italy, Hungary, Kenya, India, China, Japan, Vietnam, Thailand.

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, container, cut flowers, dried herbs (medicinal), fresh fruit, new vehicles, nursery stock, timber pallets, tissue culture.

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