Flower:

Flowers are borne on stalks up to ½ inch long, in clusters (fascicles) at the leaf axils along the stem. Flowers are ¼ inch across, mostly white or sometimes pinkish with deeper pink streaks, with 5 squarish petals, the flat tips with slight, wavy lobes. In the center is a column of white styles and stamens. The 5 sepals are densely hairy, broadly triangular and pointed, as long as or slightly shorter than the petals and visible behind the petal.

Leaves and stems:

Leaves are round to kidney shaped, nearly flat to deeply heart-shaped at the base, 1 to 3 inches wide, on stalks 3 to 6 inches long. The blade has 5 to 9 shallow, rounded or pointed lobes with sharp or blunt teeth around the edges. Upper surface is dark green with sparse scattered hairs, the lower surface lighter green and more densely hairy. The stems and leaf stalks have short, dense, woolly hairs. Stems are 4 to 24 inches long and branch out from the base, mostly spreading prostrate on the ground.

Fruit:

Fruit is flat and round, much like a wheel of cheese though its center is dimpled. The wheel is about ¼ inch across sitting in a leafy cup formed by the sepals that curl around its edge. It is divided into 13-15 seed containing carpels that split apart at maturity.

Individual carpels are crescent moon shaped, the outer surface has coarse reticulated ridges as well as radial lines in the sides.

Notes:

Round-leaved Mallow, formerly Malva rotundifolia, and its similar cousin Common Mallow (Malva neglecta) are old world introductions now widely distributed across North America. They exhibit the same weedy behavior, appearing in lawns, gardens, agricultural fields, urban waste areas, even cracks in concrete. While the leaves are very similar they are not really difficult to tell apart if flowers or fruit are present. Malva pusilla flowers are more often white and half the size of M. neglecta, which is more often pinkish. M. neglecta petals are at least twice as long as the sepals, where they are about the same length on M. pusilla. More reliable yet is the rough, reticulated outer surface of M. pusilla fruit, where M. neglecta is smooth. We have little doubt that both species are under-reported in Minnesota.