This chapter presents a discourse analytical study of explicit reference to theconcept of metaphor within a broad range of biological disciplines. The aim ofthe analysis was to study in what capacity the term ‘metaphor’ was conceptualizedand framed in actual scientific research writing, and whether the differentframings were related to the specific discipline or genre or even stage ofscientific development. Though the concept of metaphor is generally valued as ascientific heuristic resource, two distinct positions on the specific values of metaphorin science are represented in the material. The dominant position criticizesmetaphor for its open-endedness and aims at either empirically sanitizingor discarding the metaphor. A less dominant and more social-constructivepositionembraces the open-endedness as a valuable and dynamic scientific drivingforce suitable for scientific communication as well as heuristics. In either case,the explicit reference to metaphor functions as a rhetorical strategy for promotingand positioning the author’s own research.