Any of the thistles when you look at the genus Silybum.
an esculent European thistle (Silybum marianum), getting the veins of their leaves of a milky whiteness.
A thistle-like plant, Silybum (Carduus) Marianum, local in southern European countries, somewhat cultivated and spontaneous somewhere else. The leaves tend to be variegated with white. Sometimes called lady's-thistle.
any of several Old World coarse prickly-leaved bushes and subshrubs having milky liquid and yellowish flowers; commonly naturalized; frequently noxious weeds in cultivated soil
tall Old World biennial thistle with large clasping white-blotched leaves and purple rose heads; naturalized in California and south usa