A Conspectus of the North American Isoetaceae

Abstract

Isoetes (Isoetaceae; Lycopodiopsida; quillworts) constitutes a highly successful, cosmopolitan genus with over 200 species. Isoetes is derived from isos Greek for equal and eter for year, referring to the typically long persisting leaves of the sole genus in this ancient plant family. The leaves resemble a ‘quill-of-feather,’ hence the common name ‘Quillworts,’ wort, from old Germanic wurti, meaning plant. In large measure due to its simple form, inconspicuous appearance and negligible economic value, it represents one of the least studied and least collected of all North American genera. Isoetes constitutes a taxonomically enigmatic group with numerous polyploid species that arose through hybridization.