Controversial plant considered by many (boaters) to be an invasive pest, it does do a good job of wetland remediation and is not nearly as pernicious as Hydrilla.

Used as a model organism for heavy metal toxicity

The plant has been known to science for a long time, one you go back further than 1800 not much is written in English but there are ample references to it prior than this (ie. Antonii Laurentii de Jussieu - Genera plantarum secundum 1789). By the late 1800's it's usage was common in aquaria and literature and many examples abound.

It's iconic as an aquarium plant and has been used by TFH as a cover photo for the Rataj book of Aquarium Plants.

  1. The ecology of Egeria densa Planchon (Liliopsida: Alismatales): A wetland ecosystem engineer?
    Matthew Yarrow et al 2009.

  2. Competition between two invasive Hydrocharitaceae (Hydrilla verticillata (L.f.) (Royle) and Egeria densa (Planch)) as influenced by sediment fertility and season
    C Money et al 2006

  3. Phytoremediation of Silver Species by Waterweed (Egeria Densa)
    The Chemist Volume 90 | Number 1 ISSN 1945-0702

  4. Genera plantarum secundum
    Antonii Laurentii de Jussieu, 1789