Comparative spore morphology of ten species of the genus Ophioglossum L. from Kerala, India

The eusporangiate fern Ophioglossum brings some uncertainty among tax-onomists while identifying the species. Therefore, a combined approach by considering the spore morphology and other morphological characters is more authentic for delimiting species of this genus. This study documented and compared the spore morphology of O. costatum, O. gramineum, O. lusi-tanicum, O. lusoafricanum, O. parvifolium, O. pendulum, O. petiolatum, O. raphaelianum, O. reticulatum, and O. rubellum collected from Kerala, India by Scanning Electron Microscopy (SEM) analysis. SEM images of the spores for each species were provided, the P/E ratio was calculated, and the size classes of the spores were determined here. The occurance of O. lusitanicum in India was confirmed, and O. madhusoodhananii was synonymised under O. costatum.