A nomenclature survey of the genus Amaranthus (Amaranthaceae) 7: names published by Willdenow

A nomenclatural study of 12 names and designations published by C. L. Willdenow was carried out. Two designations, "Amaranthus incomptus" (nomen nudum) and "A. japonicus" (pro synonymo), are not validly published. The ten validly published names are not yet typified except for A. chlorostachys Willd. Eight of the nine untypified names (A. angustifolius M. Bieb. ex Willd., A. bicolor Nocca ex Willd., A. campestris Willd., A. inamoenus Willd., A. lateus Willd., A. polystachyus Willd., A. strictus Willd. and A. tenuifolius Willd.) are lectotypified here on specimens preserved in the Willdenow Herbarium in Berlin (B), while the other name (A. hecticus Willd.) is lectotypified here on an illustration in Willdenow's Historia Amaranthorum. All the names in Amaranthus published by Willdenow are considered here to be heterotypic synonyms of currently accepted species names. The results obtained highlight how many Amaranthus species, especially in the past. were described on the basis of characters that have low or no taxonomic value, whereas morphological characters of the flowers have a high taxonomic value.