Flower:

Flowers are about ½ inch across, tubular with 5 notched lobes. The color is pink to magenta and there are 3 to 5 long pink stamens with yellow tips. Groups of 3 or more flowers sit at the end of stems branching out in the upper part of the plant. The flowers open in late afternoon and close before noon the next day.

Leaves and stem:

Leaves are heart-shaped, 2 to 4 inches long and 1 to 3 inches wide with smooth but often wavy edges. Leaves on the lower part of the plant have short stems. Attachment is opposite. The main stem feels square or ridged but is more rounded in the upper part of the plant. Stem color is light green, sometimes striped, and often reddish at the leaf nodes. The plant is mostly hairless but there may be a few scattered hairs on the leaves or stem.

Fruit:

Seed is a hard grayish brown nutlet about ¼ inch long with 5 ribs; it is somewhat hairy.

Notes:

Wild Four O'Clock often looks bushy due to much branching. Square stems and opposite leaves are traits of plants in the Mint family, but that is not the case here.