Flower:

Clusters of stalked flowers opposite a leaf in the upper plant and at the tips of branching stems. Flowers are about ¾ inch across, star-shaped with 5 triangular petals fused in the lower half, white to violet and green at the base. The petals are mostly spreading but may be curled back. Protruding from the center are 5 stout yellow stamens surrounding a straight, slender, green style.

The calyx has 5 long lobes with a long taper to a pointed tip and typically spreading at the tip. The calyx and flower stalks are covered in star-shaped hairs and sparse prickles.

Leaves and stems:

Leaves are oblong to egg-shaped in outline, 2 to 6 inches long, up to 3 inches wide, both surfaces covered in star-shaped hairs, on a short stalk. Leaf edges are often wavy, and toothless but shallowly lobed, the lobes typically angular and resembling large teeth.

Stems and major veins on the underside of leaves are variously covered in sharp, yellowish prickles. Stems are green and covered in star-shaped hairs. Colonies may be formed from creeping rhizomes.

Fruit:

Fruit is a round berry, about ½ inch in diameter, that ripens to yellow and becomes wrinkly when mature.

Notes:

Native to the US farther south and east of Minnesota, Horse Nettle is considered adventive here, but with climate change its natural range will naturally spread northward so in a few years it might treated as a native species after all. It was once an agricultural pest and listed as a county-level noxious weed but Round-up Ready crops took care of that.