| Survey of the Plant Kingdoms | | Explores plant anatomy, taxonomy, and classification, from Monera through the higher plants. Includes descriptions as well as graphics and schematics. |
| Thomson: Free Resources | | Includes the Index to Organism Names, a publicly available subset of TRITON the Taxonomy Resource, and the Zoological Record Thesaurus. |
| Tree of Life | | Phylogenetic tree with information about the diversity of organisms on Earth, their history, and characteristics. An on-going multi-authored project hosted by the University of Arizona. |
| Utah Conservation Data Center | | Database of photos and fact sheets for animals and plants occurring in this state. Includes lists of sensitive, threatened, and endangered species. |
| Wikispecies | | Wikimedia Foundation project that aims to catalog all species. |
| World Biodiversity Database | | A growing taxonomic database and information system that aims at documenting all presently known species (about 1.7 million). Taxonomic trees, descriptions, synonyms, literature citations, and molecular database queries. |
|
|
