What Is This South Dakota Plant?

Prickly Poppy Argemone polyanthermos

Ask the Expert: Help identifying this plant?
Hi! I’m working on a project for a college class and would like to use this picture that I took on vacation in Custer St Park, SD last July, but I can’t figure out what kind of flower it is. Thanks, and I really appreciate your help!
Jenny

Plant Expert Reply:
What you have is a Prickly Poppy (Argemone polyanthemos). This plant can get 2 to 4 feet in height and 1 to 2 feet wide. It blooms June to August throughout the western part of the United States with white flowers and yellow center stamens. Normally found in full sun, it prefers dry to medium moisture and require virtually no maintenance.

For more information check out The Missouri Botanical Ga.rdens page:
http://www.mobot.org/gardinghelp/plantfinder/plant.asp?code=C817