L., Sp. Pl. 794 (1753).
Synonymy: Sonchus tenerrimus
Common name: Common sow-thistle, milk thistle.
Annual herb 20-110 cm high; stems erect, sparsely branched, hollow, smooth, glabrous; basal leaves 5-20 cm long, lacking auricles, rarely forming a rosette; cauline leaves oblanceolate to lanceolate, pinnatifid to pinnatipartite, variable in lobing, often lyrate with a broad rounded terminal segment or acute and runcinate, with acute patent auricles, 6-35 cm long, 3-12 cm wide, softly herbaceous, denticulate but never spiny, glabrous, often glaucous, prominently net-veined.
Peduncles 0.5-7 cm long, glabrous or with a few glandular hairs, with 1 bracteole; Capitula in a panicle of a few umbel-like groups; involucres 10-12 mm long; bracts glabrous or with glandular hairs along the mid-line; florets 80-230; ligules 5-6 mm long.
Achenes moderately compressed, obovoid, 2.5-3.7 mm long, rugulose all over, with very narrow margins, glabrous, brownish; pappus c. 6 mm long, persistent.
Cunningham et al. (1982) Plants of western New South Wales, p. 718.
Weed of cultivation and pastures, occurring in disturbed sites in all plant communities.
S.Aust.: NW, LE, NU, GT, FR, EA, EP, NL, MU, YP, SL, KI, SE. All States. Widespread in temperate zones of both hemispheres, probably native to Europe and south-western Asia.
Flowering time: most of the year.
SA Distribution Map based
on current data relating to
specimens held in the
State Herbarium of South Australia
A few collections appear to be intermediate between this species and S. asper; according to Boulos (1972), hybrids between these species occur but are sterile.
Not yet available