sow thistle(n = noun.plant) milk 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 kind of bush, shrub
is a member of genus sonchus, sonchus
has particulars: milkweed, sonchus oleraceus

barnaby's thistle, blessed thistle, blue thistle, boar thistle, brook thistle, bull thistle, canada thistle, carline thistle, common carline thistle, cotton thistle, creeping thistle, european woolly thistle, field thistle, globe thistle, golden thistle, holy thistle, horse thistle, lady's thistle, melancholy thistle, milk thistle, musk thistle, nodding thistle, our lady's mild thistle, plume thistle, plumed thistle, russian thistle, scotch thistle, sow, sow bug, sow in, sow one's oats, sow one's wild oats, spear thistle, stemless carline thistle, thistle, welted thistle, white thistle, woolly thistle