The taxonomy and conservation status of Isoetes (Isoetaceae; Lycopodiopsida) in India

Abstract

In many cases over the years the diversity of Isoetes in India has been defined by inconsistent morphological analyses and questionable data. This has resulted in substantial confusion, dramatically different taxonomic interpretations and a low level of global acceptance. That in turn has prevented the reliable determination of conservation priorities. The present study reviews the most reliable morphological, distributional and cytological Indian data available with techniques and standards that have guided successful taxonomic investigations of Isoetes elsewhere in the world. This results in the enumeration of nine readily distinguishable species for India. One named hybrid is also discussed as is the probable occurrence of other unnamed hybrids. All Indian Isoetes species except I. coromandelina subsp. coromandelina are endemic. Two possible but unresolved taxa are also discussed. A clearer determination of the highest national priorities for Isoetes conservation has resulted. Most Indian taxa are rare, some qualifying as Endangered and others probably being extinct. Suggestions for conservation strategies and actions to protect and sustain vulnerable Isoetes species and their habitats are offered. © 2020 Société botanique de France.