The worldwide trade in plants for use in aquaria and ponds is a multi-million dollar industry. Aquatic, semi-aquatic, and amphibious plants are exported, largely from tropical and subtropical regions, to countries around the world. This movement across international borders is of great concern, particularly since many aquatic plants have the ability to disperse widely through a remarkably effective variety of vegetative and sexual mechanisms. Serious ecological consequences can result when these plants are released into waterways, where they can become dominant and displace native plants. Many plants with origins in the aquarium trade have subsequently become serious environmental weeds in various countries, such as water hyacinth (Eichhornia crassipes), Salvinia (Salvinia molesta), East Indian Hygrophila (Hygrophila polysperma), Cabomba (Cabomba caroliniana), Asian Marshweed (Limnophila sessiliflora), water lettuce (Pistia stratiotes), and Melaleuca quinquenervia. Many more have a high potential to become invasive. Aquatic weed species on the U.S. Federal Noxious Weed list are represented in 24 of the key's genera.

This key allows you to identify genera of freshwater aquatic and wetland plants currently cultivated commercially in nurseries around the world for the aquarium and pond plant trade as well as some genera grown in private collections or in association with ornamental ponds. It attempts to capture a snapshot of the industry — to cover all the freshwater taxa in the trade as of 2017. The aquarium and pond plant industry is dynamic though; explorations are constantly undertaken to find new aquatic plants suitable for introduction to the industry, while artificial hybrids of already-established species are constantly being produced to generate new, more attractive plants.

Preventing the introduction of invasive aquatic weeds into new areas, and slowing their dispersal once introduced, requires correct identification, yet the sheer diversity and phenotypic plasticity of aquatic plants makes their identification a challenge. This key is designed to be used by people with varying degrees of knowledge, from aquatic plant hobbyists to expert botanists.

All images were produced by Shaun Winterton, except where noted in image captions. The splash screen and app icons were developed by Identic Pty. Ltd. Please see the Aquarium & Pond Plants of the World website for proper guidelines on use and citation of images.

Key author: Shaun Winterton

Fact sheet authors: Shaun Winterton and Jamie Burnett

Original source: This key is part of the complete Aquarium & Pond Plants of the World tool at https://idtools.org/id/appw/

This Lucid Mobile key was developed in cooperation with the USDA APHIS Identification Technology Program (ITP). Please visit https://idtools.org to learn more.

For more information on the Lucid suite of tools please visit https://www.lucidcentral.org