Abstract
Four Alismataceae names from the Americas are investigated. Second‐step lectotypes are designated for Hydrocleys martii and Sagittaria seubertiana according to the Art. 9.17 of Madrid Code . A lectotype is designated for Sagittaria isoetiformis , resolving a 130‐year nomenclatural ambiguity. Finally, the previously proposed neotypification for Sagittaria chilensis was superseded since the discovery of original materials at HAL, G‐DC, and SI herbaria. These nomenclatural actions contribute to the stabilization of some Alismataceae in the Western Hemisphere, providing a solid foundation for future taxonomic studies.