Tool background and scope

Aquarium and Pond Plants of the World (APPW) is a tool to aid in the identification of aquatic plants used in the aquarium and pond plant trade worldwide. This tool includes an interactive identification key, over 300 informational pages, and over 1800 images. The first edition of this tool (Winterton, S. (April 2004) Aquarium and Pond Plants of the World, Lucid v. 2.1 and v. 3.1, North Carolina State University (NCSU), and USDA/APHIS/PPQ Center for Plant Health Science and Technology (CPHST)) was developed and published by CPHST as part of its cooperative agreement with NCSU. Edition 2.0, an update to the first edition, was developed and published by CPHST in collaboration with the California Department of Food and Agriculture (CDFA) in November 2007. The USDA APHIS PPQ Identification Technology Program (ITP) released an updated interface, Edition 2.1, for the tool in August 2015. See the tool updates page for details on the newer editions.

The two authors of APPW Edition 2 are Shaun Winterton and Julia Scher. At the time of Edition 2 publication, Shaun Winterton was a Principal Entomologist with the Queensland Department of Primary Industries & Fisheries, Brisbane, Australia, and Julia Scher was a member of CPHST's laboratory in Fort Collins, CO but was based at the Seed Lab in CDFA's Plant Pest Diagnostics Center. At the time of Edition 2.1 publication, Shaun Winterton was a member of the CDFA Seed Lab, and Julia Scher was based at the CPHST Fort Collins lab.

For information concerning Aquarium and Pond Plants of the World and to offer any feedback or comments, please contact ITP at


Who should use APPW?

Aquarium and Pond Plants of the World is designed specifically for United States quarantine officials responsible for inspecting shipments and identifying aquatic plants imported or exported for sale in the aquarium and pond plant industry worldwide. Federal, state and local officials conducting domestic surveys within the United States may also find APPW useful, and its worldwide scope allows APPW to be used by quarantine officials in other countries around the world. Additionally, APPW can be used by aquatic plant nurseries for information about invasive species, and to confirm or make identifications of plants in their stocks or new acquisitions.

Taxonomic scope: which genera are included in APPW?

This identification guide aims to cover all aquatic plants currently cultivated in the freshwater aquarium and pond plant trade around the world. Most aquatic plants covered are commonly found in the trade, but APPW also includes those that are uncommon to rarely seen. The number of aquatic plants worldwide is enormous, but only the genera of aquatic plant species included on price lists of wholesalers or retailers of aquarium and pond plants worldwide are included here.

The term "plant" is used rather broadly here; the taxonomic scope is not restricted to flowering plants (angiosperms). Non-angiosperm aquatic plants covered in APPW include genera of mosses, liverworts, ferns, horsetails, and quillworts. Macroalgae, which are not plants, are also included.

The term "aquatic" is also used broadly to include not just plants that must grow in water, but also semi-aquatics, amphibious plants, and some terrestrial plants that can tolerate some inundation (see more about aquatic plants). In short, APPW covers plants that can be grown in an aquarium, or in a pond or around the pond's margin.

APPW is restricted to freshwater aquatic plants in the trade; marine plants (known as seagrasses) such as Zostera, Thalassia, Poseidon, Halophila, etc. are not included, nor are marine macroalgae (e.g. Botryocladia, Halimeda, Haliptilon, Udotea, etc.), with the exception of Caulerpa.

In choosing genera to include in APPW, an attempt was made to capture a snapshot of the industry -- to cover all the freshwater taxa in the trade in 2006. However, the aquarium and pond plant industry is dynamic; explorations are constantly undertaken to find new aquatic plants suitable for introduction to the hobby, while artificial hybrids of already established species are produced to generate new, more attractive plants. It is inevitable that genera and species will enter the trade that are not covered here. The second edition (2.0) included 16 new genera; more genera may be added in subsequent editions.