Bernice Bjornson had this this to say about the species in 1946:  “Knotwood or doorweed is a familiar weed, sometimes invading lawns, especially if they are not well watered, and forming mats even on dirt paths where it seems not to mind being trampled.  Its leaves are oblong to lance-shaped, acute at the end; its flowers are small, pinkish margined, usually one in every leaf axil toward the end of the branch.  “Aviculare”, the species name, means “small birds”.  Birds eat the seeds of knotweed.”