On the parallel emergence of circular systematics: mycology, zoology, and continuity, 1819–1837

In 1821, the Swedish mycologist Elias Magnus Fries advanced an elaborate classification system of fungi, one that would eventually contribute to his colloquial dubbing as the ‘Linnaeus of Mycology’. In its most basic form, Fries’s system divided all fungal taxa into precisely four component parts. More fateful, however, was Fries’s arrangement of those groups into circles of relationships, just two years after the Scottish entomologist William Sharp Macleay published his provocative ‘circular and quinary’ system in 1819. The parallel advancement of two circular classification schemes worked to mutually buttress the credibility of each—giving many the appearance of a striking independent discovery. This article examines Fries and Macleay’s systems, attending to the questions: How was it that two naturalists, working in entirely different contexts, developed novel circular classification systems within such a short span of time? In what ways did their theories overlap in their claims about the order of nature, and how did they differ? Ultimately, it aims to provide a fresh account of how circular systems—now considered a strange vestige of a troubled period in natural history—emerged so rapidly, and subsequently garnered such dramatic attention and enthusiasm from leading naturalists of the time.