The Linnaean names Malva abutiloides, Sida alba, Sida americana, and Sida triquetra are investigated. Sida alba is a nomen nudum and not validly published according to the Art. 38.1 of the International Code of Nomenclature for algae, fungi, and plants. Sida triquetra is a superfluous and illegitimate name, replacement of the legitimate Sida trisulcata by Jacquin. The name S. americana is lectotypified by a specimen kept at LINN (No. 866.25). For nomenclatural purposes, the names Abutilon dentatum (= A. abutiloides), Albutilon ramosissimum (= S. trisulcata), Sida tricuspidata (= A. abutiloides), and Sida lignosa (= A. abutiloides) were also studied. These four names are lectotypified by specimens preserved at US (A. dentatum), PR (A. ramosissimum), and MA (S. tricuspidata and S. lignosa).