Aerva lanata (mountain knotgrass) is a woody, prostrate or succulent, perennial herb in the Amaranthaceae family of the genus Aerva, native to Asia, Africa, and Australia. The plant sometimes flowers in the first year.

A. lanata is a common weed which grows wild everywhere in the plains of India. The root has a camphor-like aroma. The dried flowers which look like soft spikes, are sold under the commercial names Buikallan and Boor. It is one of the plants included in Dasapushpam, the ten sacred flowers of Kerala.