Isaac Newton’s theory of how water defies gravity in plants

Newton's journal

Under the heading “Vegetables,” page 102 of Newton’s journal reads: “Suppose a b the pore of a Vegitable filled with fluid mater & that the Globule c doth hitt away the particle b, then the rest of subtile matter in the pores riseth from a towards b. & by this meanes juices continually arise up from the roots of trees upward leaving dreggs in the pores & then wanting passage stretch the pores to make them as wide as before they were clogged. which makes the plant bigger untill the pores are too narow for the juice to arise through the pores & then the plant ceaseth to grow any more.”

Image provided with permission from the Syndics of the Cambridge University Library

Isaac Newton had a clue about how plants transport water 200 years before botanists. David Beerling, a plant scientist at the University of Sheffield in England, argues in the Feb. 2 Nature Plants that Newton’s notes on plant sap in the 1660s presage modern theories of plant hydrodynamics.

A page in one of Newton’s undergraduate notebooks describes plant sap rising up through pores in the plant’s stem, drawn by solar energy. The ideas are in line with the modern understanding that evaporation in tree leaves pulls water up through a plant against gravity.

Helen Thompson is the multimedia editor. She has undergraduate degrees in biology and English from Trinity University and a master’s degree in science writing from Johns Hopkins University.

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