'white thistle' definitions:

Any plant of the genus Argemone having large white or yellow flowers and prickly leaves and stems and pods; chiefly of tropical America [syn: prickly poppy, argemone, white thistle, devil's fig]

Spiny shrub with silvery-scurfy foliage of alkaline plains of southwestern United States and Mexico [syn: quail bush, quail brush, white thistle, Atriplex lentiformis]