The large white flowers of argemone munita
have six petals, in contrast to most other species of this genus, which have four. Petals are between 1 and 1.5 inches in length, have a somewhat wrinkled, grooved texture, and surround a spherical cluster of 150 to 250 yellow stamens and a red pistil which is divided into 3 to 5 chambers. Underneath are three pointed sepals. Stems contain yellow sap. The lobed leaves have long, light-colored prickles on the margins and both surfaces, mostly along the veins. Stems are also prickly, sparingly to densely covered. The prickles are unequal in length.
There are four subspecies (robusta, munita, rotundata, argentea, of which the last is most widespread), differing in the density of prickles, the distribution of the prickles on the leaves, the length of the prickles and the color of the stems.