Spiny sowthistle (Prickly sowthistle)
Sonchus asper

Description
Herbaceous annual plant which can reach 150 cm (59.05 inch) in height. It forms a deep taproot.

Characteristic Features
Leaves with prickly margins that initially develop as a basal rosette and then occur alternately along the flowering stem, bluish-green color of the leaves, and yellow flowers with a 'puff-ball' seedhead.

Young Plant
Young leaves form a basal rosette. Both young leaves and cotyledons have a whitish coating.

Cotyledons
Egg-shaped, approximately 3 to 8 mm (0.12 - 0.31 inch) long, occur on petioles.

Stems
Erect, 25 cm - 150 cm (9.84 - 59.05 inch) tall, branched in the inflorescence.

Leaves
Alternate, sessile, clasping, auriculate, with undulate spiny margins, deep shiny green above, glaucous below.
Lowest leaves obovate to spatulate or somewhat lyrate-pinnatifid, to +15 cm (5.9 inch) long.
Upper leaves reduced, becoming ovate-lanceolate.
Auricles spiny but round at the apex.