A Synopsis of the Genus Chara, Series Gymnobasalia (Subsection Willdenowia Rdw)

The series Gymnobasalia, a sharply differentiated subgeneric complex within the genus Chara, consists of at least seven morphologically distinct species. All seven species are reproductively isolated from one another. No evidence of even limited hybridization between the seven was encountered. The two dioecious members of the complex occupy restricted and, possibly partially overlapping ranges in South America. Monoecious members are in general more widely distributed but still appear to have originated in Central or South America. The holotype of C. zeylanica Klein ex Willdenow was examined and found to be tetrascutate. For the abundant and widely distributed monoecious‐conjoined, octoscutate member of the complex, previously shown to be distinct from C. zeylanica, the earlier name C. haitensis Turpin is here validated. Chara foliolosa Muhl. ex Willdenow is considered conspecific with, but to hold priority over, C. sejuncta Braun.