Other names: Prickly Sow-thistle, Milk Thistle.
Family: Asteraceae (Daisy family). Native of Europe.
Occurrence: Widespread weed in disturbed bushland, roadsides and waste areas. It is also an environmental weed.
This is a variable species, with two subspecies occurring in Central Victoria.
Subspecies asper: A slender annual. Stem is less than 1 cm in diameter. Leaves are mostly along the stem, and are shallowly lobed.
Subspecies glaucescens: A robust annual or biennial. Stem is 1 to 2 cm in diameter. Leaves are in a basal rosette and along the stems. Leaves leathery, often bluish. Leaves deeply lobed.
Similar species: The very common Sow Thistle (*Sonchus oleraceus) has leaves which are variably lobed and are toothed, but the margins are not spiny. The leaves are not rounded at the base but pointed.