Arabis aculeolata is a species of flowering plant in the mustard family known by the common name Waldo rockcress. It is native to a small range in the mountains of southern Oregon, where it is an uncommon member of the serpentine soils flora. Reports of its occurrence in Del Norte County, California are unconfirmed. This is a perennial herb growing from a tough caudex covered in large hairs and the bases of leaves shed in previous seasons. It produces one or more erect stems to heights between 20 and 35 centimeters. The stems are dark in color, often reddish or purplish, and are coated in stiff white hairs. The leaves form a basal rosette about the caudex. They are oval-shaped, green in color and sparsely covered in coarse white hairs, up to 4 centimeters long, and with smooth or wavy edge