Flower:

Flowers are showy, 1½ to 2 inches across, with 7 or more yellow petals that are sometimes reddish at the base. A green ovary protrudes in the center, surrounded by numerous white or red stamens with yellow tips. Flowers are few; many plants have no flowers or do not flower every year.

Leaves and stem:

With cacti, the spines are modified leaves and the fleshy pad segments are modified stems. Spines are up to 1 inch long, sometimes longer than the pad, and typically straight, clustered in groups of 3 to 8, growing from numerous small projections (areoles) on the surface of the pad. The spines are not hooked but the areoles have tiny barbs (glochids) at the base of the spine cluster that easily detach and can be difficult to see, let alone remove once embedded in skin. The pads are a dull dark green, generally a somewhat flattened oval to elliptic shape, up to 2 inches long and ½ to 1 inch wide with a waxy surface. The segments detach very easily from each other. Plants are sprawling and can form a mat up to 2 feet across.

Notes:

There are 3 species of prickly pear cactus native to Minnesota, and about a dozen in North America. The flowers of the 3 natives are more or less the same. Distinguishing features are mostly the size and shape of the pads and number of spines. Plains Prickly Pear has larger and more numerous flowers and much larger pads that do not easily detach, with up to 6 spines per areole. O. humifusa has less densely crowded areoles with 0 to 2 spines each. When I discovered a small patch of Brittle Prickly Pear in the grass, I went to remove a rogue blade of grass before taking a photo and ever so slightly touched the spines of one of the end pads. It immediately broke off the rest of the plant and stuck to my hand. Ouch. Detaching like this is how it mostly spreads; the pads reroot themselves where they drop.