Flower:

Elongating racemes at the top of the plant. Flowers are tiny with 4 spreading, pale yellow, mostly linear-oblong petals notched at the tip. In the center are 6 yellow stamens and a stout green style. The 4 sepals surrounding the base of the flower are oblong to egg-shaped and green. Flower stalks are spreading to ascending, up to ~¼ inch (2 to 5 mm) long; stalks and sepals are covered in a mix of star-shaped, forked and unbranched hairs. The racemes elongate as the plant matures, with a tight round cluster of open flowers at the tip, spent flowers fading to white, and fruit forming below.

Leaves and stems:

Leaves are alternate, 1 to 1¾ inches (3 to 4.5 cm) long, less than ¼ inch (.5 to 5 mm) wide, mostly broadest above the middle, rounded to pointed at the tip, tapering at the base, short-stalked to stalkless. Edges are toothless, surfaces are covered in star-shaped hairs with 6 to 10 rays. Stems are single or multiple from the base, erect, ascending, or prostrate from the base and rising near the tip (decumbent), branched or not, and densely covered in star-shaped hairs.

Fruit:

Fruit is a 2-chambered capsule less than ¼ inch (3 to 4 mm) long, longer than the persistent sepals, round in outline, flattened around the edges and bulging in the center as seed develops, the remains of the persistent style at the tip, and the surface sparsely to moderately covered in star-shaped hairs. Inside the capsule are 4 oval-oblong seeds.

Notes:

Pale Madwort is an occasional weed found on roadsides, agricultural fields, gravel pits, parking lots and other areas with disturbed soils, and, like many weeds, is no doubt under-reported in the state. It is very similar to the related Desert Madwort (Alyssum desertorum), which is much like it in all respects except its capsules are smooth and sepals wither away as fruit develops. We've encountered both species at various campgrounds in Minnesota, where weed seed is often transported on car tires.