Flower:

Loose, elongating raceme at the top of the plant and sometimes arising from upper leaf axils. Flowers are 1/3 to ½ inch across with 4 narrow, spreading petals and 6 yellow-tipped stamens. Petal color is usually white, occasionally lavender.

Surrounding the flower are 4 erect, hairless sepals half or so as long as the petals, oblong-elliptic with rounded tips, light green with white edging. The flowers are mostly erect, on slender, hairless stalks up to about ¾ inch long.

Leaves and stems:

Basal leaves are up to 3 inches long and 3/8 inch wide, spatula shaped, widest above the middle, tapering to a slender stalk. Edges are toothless or with small sharply pointed teeth and may be fringed with sparse hairs, sometimes just along the stalk. Surfaces are hairless or sparsely hairy with 2-rayed hairs.

Stem leaves are erect, up to 3 inches long, narrowly lance-oblong, hairless, mostly toothless or rarely with a few teeth, blunt to pointed at the tip, stalkless and with 2 lobes at the base (auricles) up to 3 mm long. Leaves are usually crowded near the base and more widely spaced above. Stems are single or a few from the base, mostly smooth but may have sparse 2-rayed hairs at the base. Leaves and stems are green, green tinged purple, or dark purple.

Fruit:

Fruit is a slender, 2-sectioned pod 2 to 4 inches long, erect and mostly hugging the stem.

Seeds are up to 2.2 mm long, oval with a distinct, broad papery wing around the edge, and overlapping in 2 rows in each section of the pod.

Notes:

Drummond's Rock Cress, formerly known as Arabis drummondii, is an uncommon species in Minnesota, found in gravelly prairies, rock outcrops, and open woods, often in somewhat disturbed soils. It is distinguished from other Minnesota Rock Cress species by the erect fruits, auricled stem leaves, and mostly hairless stem and leaves, except for sparse 2-rayed hairs at the base of the plant. When not fruiting, it somewhat resembles the much more common Spreading-pod Rock Cress (Boechera grahamii), which has spreading to drooping flowers and hairier basal leaves, the hairs usually with more than 2 rays. The erect fruits are similar to Tower Mustard (Turritis glabra) and Hairy Rock Cress (Arabis pycnocarpa), both of which have much smaller flowers and broader, hairier leaves.