2010 Volume 61 Issue 2 Pages 75-86
Herbarium specimens referable to Ceratopteris thalictroides in the sense of Lloyd were examined and the following cryptic taxa were recognized; C. thalictroides, C. gaudichaudii var. gaudichaudii, C. gaudichaudii var. vulgaris (var. nov.), C. oblongiloba (sp. nov.), and C. froesii. Compared with C. thalictroides s.str., C. gaudichaudii var. vulgaris is basically characterized by short stipes and dense pinnae, while C. oblongiloba is characterized by dense pinnules and narrowly oblong terminal lobes. A key to distinguish them and descriptions of the taxa are presented.