Quillwort

Isoetes, commonly called quillworts, is a genus of lycopods and the only living genus in the family Isoetaceae and order Isoetales, with about 200 recognized species distributed worldwide as of 2016. The plants are mostly aquatic or semi-aquatic, growing in clear ponds and slow-moving streams, though some species tolerate seasonally dry ground, and are marked by hollow, quill-like leaves arising from a central underground structure. Quillworts reproduce by spores dispersed largely through water, and represent an ancient lineage, with species virtually identical to modern quillworts known from the Jurassic.