Sonchus arvensis L.
perennial sow thistle
Perennial. Roots creeping, perennating. Stem erect, simple or branched, finely grooved or ribbed, glabrous, 50-120 cm tall. Lvs firm, dark green, paler beneath, glabrous, oblong-lanceolate to lanceolate; margins coarsely dentate. Rosette and lower stem lvs tapering to base, 15-35 × 3-10 cm, pinnatifid to c. 1/2way to midrib; lobes deflexed, triangular to oblong. Upper lvs becoming less lobed, narrow-triangular to subulate, with rounded amplexicaul auricles at base. Infl. cymose-paniculate; capitula numerous. Involucre 15-18 mm long, turbinate to cylindric; bracts imbricate, spreading at fruiting, with tangled white short branching hairs and long yellow glandular setae. Receptacle with short scales and fine sparse short hairs. Florets 11/2× length of involucre; corolla tube a little > ligule; ligules spreading, yellow. Achenes elliptic, brown, weakly flattened, 3.5-3.8 × c. 1.5 mm, 5-ribbed on each face, not winged; ribs and spaces between conspicuously closely wrinkled. Pappus fine, white, = involucre.
N.: Hawke's Bay (near Taradale); S.: Canterbury (vicinity of Christchurch, Springston), Otago (Waipiata, Catlins R. mouth).
Europe, W. and S.W. Asia 1855
Roadsides, hedges, swamps, cultivated land.
FL Jan-Feb FT Feb-Mar.
