What is "isoetes"

Isoetes, commonly known as the quillworts, is a genus of plants in the class Isoetopsida and order Isoetales. They are lycopods and the only genus in Isoetaceae. There are about 140 known species, with a cosmopolitan distribution but often scarce to rare. Some botanists split the genus, separating two South American species into the genus Stylites, although molecular data place these species among other species of Isoetes, so the genus does not warrant taxonomic recognition.

The name of the genus may also be spelled Isoëtes. The diaeresis (two dots over the e) indicate that the o and the e are to be pronounced in two distinct syllables. Including this in print is optional; either spelling (Isoetes or Isoëtes) is correct.