Abstract

Nine types of taxonomic keys have been listed from the literature. These are the dichotomous, numerical, multi-access table of identification, punched-card, columnar-diagram, graphical, flow-chart, pictorial-diagram and circular-diagram keys. In this study, each type of key was observed at two levels namely, its format (which is its peculiarity, depicting the general plan, arrangement or organization of its elements) and style (which is one-to-several structural variants in which a key format may be presented in printable form). The format of each type of key along with its representative styles (which determines whether a key is single-access or multiple-access) is illustrated using anatomical features of six Nigerian species of Ocimum L., four of Hyptis Jacq., and 12 of Ficus L. The systematic mode of application and spectrum of usage of each key are discussed and the users’ opinions on its usability, efficiency, prospects, users’ familiarity and general acceptability are presented. The strengths and limitations of the key formats are also evaluated and discussed on the basis of which taxonomists are charged to consider research efforts towards improving upon the qualities, and devising new key formats with the prospect for better performance.

Key words: Artificial key, diagnostic key, Ficus, leaf epidermis, plant identification, taxonomic key, wood anatomy, Hyptis, Ocimum.