Data on species plasticity and stable characters has an overall importance in identification keys: comments on Brullo et al. (2022) article

Abstract

The genus Elatine L. consists of ephemeral species of wet-land habitats that live in the temperate regions of both hemispheres. Because of their relatively fast life cycle and small habit, they lead inconspicuous lives, which is probably why they have been relatively little studied in European botany. Although the botanists of the 19 th and early 20 th century discovered all the currently recognised taxa, there were only a few studies that specifically addressed questions on their bi - ology. This lack of detailed knowledge triggered the more recent interest in this genus (especially the European members)