A multiple access key, or polyclave, and a traditional dichotomous key were constructed for the identification of 40 species of weed seedlings. The polyclave contained 3.4 times more information than the dichotomous key; however, there was no difference in the frequency of accurate identifications or in the time required to make accurate identifications using either system. The relative values of traditional keys and polyclaves for weed seedling identifications are discussed.