Flower:

Loose, elongating clusters of stalked flowers at the ends of branching stems. Flowers are ¼ to ½ inch across with 4 rounded white petals and 6 yellow stamens. The 4 sepals behind the flower are half as long as the petals or less.

Leaves and stems:

Leaves are mostly basal, with a few leaves widely spaced along the stem. Basal leaves are up to 2 inches long, covered in short stiff hairs with a large lobe at the tip and usually at least one pair of short, oblong lateral lobes, and a short stalk. The basal leaves typically wither away by flowering time.

Stem leaves are about 1 inch long, linear-elliptic to narrowly spatula shaped, mostly toothless, hairless, stalkless, and widely spaced on the stem. Stems are hairless in the upper plant and usually hairy to some degree near the base. Multiple stems may arise from the base, erect, or prostrate but rising near the tip (decumbent).

Fruit:

Fruit is a slender pod about 1 inch long, held at about the same angle as the associated flower stalk, pointing upward. The pods become flattened as they ripen,

Notes:

Lyre-leaved Rock Cress, formerly Arabis lyrata, can be seen (among other places) along the St. Croix River, seemingly growing out of the solid rock of the cliff face along the river. It resembles Mouse-ear Cress (Arabidopsis thaliana), which has smaller flowers, broader stem leaves, unlobed basal leaves, has a preference for disturbed soil, and is more likely to colonize than Lyre-leaved Rock Cress. Flora of North America recognizes 3 subspecies, with subsp. lyrata found in Minnesota, the other 2 found farther north and west in North America as well as in northern Europe and Asia.