Léo Lesquereux, a palaeobotanist, grew up in Fleurier, a small Swiss town where his father was one of a Huguenot community of watchmakers. Young Leo loved roaming the cliffs and bogs of the region. At age seven, one of his explorations ended in a fall from a precipice; he survived but spent two weeks in a coma. He nevertheless persisted in his interest in bogs and devised a sort of augur to investigate their stratification that led to an understanding of the causes of peat formation and eventually to its relationship to the geology of coal.
He went to the University of Neuchatel where his theory met with skepticism but where he benefitted from the teaching of Louis Agassiz. He was appointed to chair at La Chaux de Fonds when tragedy struck: a Parisian doctor bungled treatment of an ear infection, leaving Lesguereux stone deaf for life and unemployed. He fell back on the family métier of watch-engraving but soon became despondent. His wife, the daughter of a Prussian general, not only nursed him but taught herself watch-engraving to support the family. After his recovery, he taught himself to lip-read in French, English and German so well that people often did not realize he was deaf.
His fortunes turned when the king of Prussia commissioned him to report on the peat bogs of the kingdom. He also examined bogs in the United States and Canada, and decided to follow his former teacher Agassiz to North America. He and his family moved to Columbus, Ohio, in 1848 where he began a watch business with his sons. Though poor at first, he was soon doing well enough to devote his energies to science. He became recognized as a pioneer of palaeobotany, contributing 12 important works. He was elected a member of the American Philosophical Society in 1861 and of the National Academy of Sciences in 1864. At his death in 1883 at the age of 83, J. P. Lesley wrote his obituary for the Proceedings of the American Philosophical Society.