Plants and laboratories: the ascent of sap between physics and vegetal physiology

The ascent of sap in plants represented a puzzle in early modern studies of nature. Although philosophers, gardeners and naturalists had traditionally explained it as a process of fermentation caused by the Sun, an alternative view emerged in combination with the physical studies of pressure. This latter field of experimentation somehow influenced the study of plants. While the mathematical study of liquids gained momentum, scholars started to apply these rules to vegetal processes, comparing pipes with plant vessels and making plants the objects of their laboratory. In this article, I explore the various ways in which scholars dealt with this phenomenon, following the physics of the equilibrium and motion of liquids, and especially through the two alternative interpretations-one developing in Italy, and one north of the Alps-that characterized the seventeenth-century study of liquids. I focus on Nehemiah Grew's and Marcello Malpighi's different interpretations of the ascent of sap in plants, as they were two major actors in seventeenth-century botanical studies, and how much they drew their interpretations from experiments in the laboratory.