Synonyms for Cudweed (same or very similar meaning)
WordNet sense 1 (any plant of the genus Filago having capitate clusters of small woolly flower heads):
filago, cotton roseWordNet sense 2 (perennial cottony-white herb of southwestern United States):
western mugwort, Artemisia gnaphalodes, Artemisia ludoviciana, prairie sage, white sageFrom the ODE community, based on WordNetadd/edit