Beyond Phragmites and Typha: A Global Bibliometric Analysis and Strategic Selection of Pioneer Macrophytes for Wastewater Treatment

Rising global wastewater generation is damaging aquatic ecosystems resulting in the need for sustainable treatment options, such as Constructed Wetlands (CWs). At this time, phytoremediation is primarily relying on a few predominant plant species ("monoculture"). This research maps the current global research landscape (1969–2025) to identify neglected "pioneer" macrophyte species to expand treatment options for CWs and quantify species saturation. A complete multi-database search (Scopus, Web of Science, OpenAlex) was performed, and after extensive harmonization in R software, the corpus was comprised of 37,379 unique documents detailing the environmental use of over 100 plant genera. Results indicate overwhelming research saturation for Phragmites australis (877 papers), Eichhornia crassipes (534), and Typha latifolia (370) compared to the cluster of "pioneer" candidates, which are rarely cited (< 10 times for each) and have only recently emerged (e.g., Mentha aquatica, Salicornia persica, Cyperus eragrostis ). Although current "star" species comprise the majority of the existing knowledge base, these plants may not have the desired resilience to certain abiotic conditions (e.g., high salinity). Conversely, the currently undefinable "pioneer" species also represent an untapped potential reservoir, however hypothetical, for application in CW phytoremediation. This analysis offers a foundation for future experimental validation of the identified "pioneer" candidates to facilitate advancements in phytotechnologies and extend the biological applications beyond what is currently known.