Tertiary Isoetes from Tasmania

Abstract

Leaves and megaspores for the Late Oligocene — Early Miocene Monpellyata flora are assigned to the new species Isoetes reticulata. This represents the first Tertiary macrofossil evidence for the genus in Australia. The species is distinct from all extant species of Isoetes in southern Australia and does not closely resemble any extant species so far examined. The lack of stomates on the leaves of I. reticulata suggests that the species grew wholly submerged in water, and this, along with the excellent state of preservation, adds to evidence indicating that the depositional site was equivalent to an extant alpine or sub-alpine lake with Isoetes growing in situ.