Interactive (multi-access) identification keys provide a computer-based approach for identifying unknown specimens. Interactive keys expedite, often greatly, the rate at which identifications can be made. They will play a major role in the future of descriptive biological systematics, and increasingly are supplementing traditional (paper-based) dichotomous identification keys. Their greatest utility is in a web-based format that is accessible to all. Interactive keys are also being used as teaching tools in taxonomy. An interactive key to families of vascular plants of Colorado is presented. It is the first phase of the Colorado Interactive Flora (CIF) project, currently in progress at the University of Northern Colorado. When completed, the CIF will be an interactive key to all taxa in Colorado. The key includes 131 families and largely follows the Angiosperm Phylogeny Group. The key uses Lucid software, a feature-rich program easily learned by authors and users. In brief, the user selects character states in any order until only one taxon remains. Lucid is forgiving, allowing the user to misinterpret some character states and still make a correct identification. It has many other features to help the user make a correct identification. Compared to dichotomous keys, interactive keys are more information-rich, have equal or greater technical precision, and are far more user-friendly. The CIF family key has non-technical descriptive terms in parentheses after the character states to make it more accessible to non-taxonomists, such as students, teachers, horticulturalists, public land managers, etc. The CIF will ultimately be placed on-line. A laptop with the family key will be available for use accompanying the poster, and will allow those interested to learn about Lucid.

Key words: bioinformatics, Colorado, interactive keys, plant systematics