milk thistle

Noun milk thistle has 2 senses

• milk thistle(n = noun.plant) sow thistle - any of several Old World coarse prickly-leaved shrubs and subshrubs having milky juice and yellow flowers; widely naturalized; often noxious weeds in cultivated soil;
is a member of genus sonchus, sonchus
has particulars: milkweed, sonchus oleraceus
is a kind of bush, shrub

• milk thistle(n = noun.plant) blessed thistle, holy thistle, lady's thistle, our lady's mild thistle, silybum marianum - tall Old World biennial thistle with large clasping white-blotched leaves and purple flower heads; naturalized in California and South America;
is a member of genus silybum, silybum
is a kind of herb, herbaceous plant