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Plants of the World Online (POWO)

A database of plant names and taxonomy, with global scope.

Website: https://powo.science.kew.org/

POWO is a database of plant names and taxonomy maintained by the Royal Botanical Gardens in Kew, London. POWO uses the taxonomic backbone maintained by the International Plant Name Index (IPNI), which is a collaboration of the The Royal Botanic Gardens at Kew, The Harvard University Herbaria, and The Australian National Herbarium.

Although no source is perfect, POWO/INPI often have the most up-to-date taxonomic backbone of any plant website or database, reflecting newer information and reclassifications, and most closely matching the current scientific consensus, whereas other sources tend to lag behind in their updates. Although we do not always defer to POWO/INPI, when there is a disagreement we use their scheme more often than not.

The core features in POWO focus on plant taxonomy, including a section on recognized subspecies or varieties, and a comprehensive list of synonyms. This aspect of the site is the most consistently complete and highest-quality aspect of the site. It is also interlinked with INPI in a way that can makes it easy to access the original works where a particular name was published.

In most cases, POWO also has other information on each taxon, usually including plant distribution information. Although the scale of this information is much coarser than that provided by USDA PLANTS, BONAP, and our range maps, it is global in scope and as such often is one of the best and most comprehensive resources for researching plants globally. However, within the US, the information on plant's range and establishment means (native vs. introduced) provided by POWO is often incomplete, inaccurate, or outdated relative to the information provided by BONAP and/or other local or regional sources.

Sometimes POWO has images of plants, and in a few cases, POWO also has an article about the plant or other information, but the presence of this additional information is spotty and inconsistent.

Another weakness of POWO is that, in the case of taxa that have been split, merged, and/or renamed, the site provides no sourcing whatsoever to explain or justify the choices they have made. There is also no published record of history of changes, nor any discussion of the relationship between POWO's treatment and that of other authorities. As such, when there are disputed, majorly changing, or otherwise complicated taxa, POWO's records can often be puzzling and leave little clue as to the relationships between their treatments and those of other authorities.