Vegetative key to the families

LATEX (milky white or yellow) present in stem and leaves
Herbs
Either; leaves all basal or basal and cauline; or, all cauline and exceeding 5 cm long
Leaves with bristly hairs on the petioles; or leaves blue-glaucous; or leaves mottled with white and less than 4 cm wide (including the spines on the margins) Papaveraceae
Leaves glabrous or with prickly hairs on the blades, c. 10 cm wide, the petioles not bristly-hairy nor the leaves mottled with yellow (Sylibum, tribe Lactuceae) Asteraceae