| Characters | Sonchus asper | Sonchus brachyotus | Sonchus oleraceus | Sonchus wightianus |
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| Plant | | | | |
| Leaves | Annual herb, 15-70 cm high. | Perennial erect herb, 10-100 cm high, with thick tap roots. | Annual erect branched herb, 20-70 cm high. | Perennial erect herb, 30-100 cm high, with creepig root stock. |
| Heads | Lower leaves oblanceolate or spathulate, lobed or undivided, middle leaves often runicinate-pinnatifid, basal leaves dentate or subspinose at margins. | Basal in rosette, middle leaves oblong or Spathulate oblong, upper leaves linear. | Cauline, sessile, amplexicaul, ovate-oblong, with acute auricles, margins runcinate, upper leaves lanceolate. | Linear-oblanceolate, lower leaves entire or pinnatifid with 4-5 pairs of lobes, middle and upper leaves lanceolate, acuminate, margins denticulate. |
| Achenes | 15 mm in diam, glandular peduncle; Involucral bracts many seriate; Corolla pubescent. | 15 mm in diam., on glandular hispid peduncles; Involucral bracts many seriate, Corolla bright yellow. | 1 cm in diam, in open panicles, peduncles glandular or eglandular-hairy, Involucral bracts many seriate. | 2 cm in diam, corymbose, peduncle glandualr hairy, Involucral bracts many seriate; Corolla sparsely pubescent. |
| | 2.5-3.0 mm long, obovate, narrowly winged, 3 ribbed on each side, brown. | 3 mm long, linear-oblong, transversely rugose, 5-ribbed, brown. | 3 mm long, compressed, rugose, 3 ribbed, minutely muricate between the ribs. | 2.5 mm long, narrowly ellipsoid, tetragonous, transversal rugose. |
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