Research project Evolution and Diversity in Isoetes (Isoetales)

The genus comprises about 200 species with cosmopolitan distribution, and is the only remaining representative of the rhizomorphic lycopsids (Isoetales), an ancient clade that also includes the well-known tree-lycopods from the Carboniferous period.

Recent studies in my group have surprisingly shown that the critically endangered and poorly known Isoetes wormaldii, only known from one or two small populations in Eastern Cape, South Africa, is the lone sister-species to the remaining Isoetes. The age of the living clade of Isoetes has been difficult to estimate but is, according to most recent results, from the Mesozoic with several major subclades being older than the final rifting of the Gondwanan super continent. This ancient origin stands in sharp contrast to the observed low morphological and molecular divergence within the genus. The project started 2000 and the end date for this project has not yet been determined.

The photo below shows Isoetes wormaldii in its natural habitat in South Africa. From Larsén et al. in BMC Ecology and Evolution (2022). Photos: Tony Dold (Rhodes University) and Eva Larsén.