Henslow, John Stevens

(b. Rochester, Kent, England, 6 February 1796; d. Hitcham, Suffolk, England, 16 May 1861)

botany.

Henslow was the eldest of eleven children of John Prentis Henslow, a solicitor. He was educated at the Free School at Rochester and later at Camberwell in Surrey, where his inherent love of nature developed into a keen interest in natural history. In 1814 he entered St. John’s College, Cambridge, and four years later graduated sixteenth wrangler; he received the M.A. in 1821. At Cambridge he studied mathematics, chemistry, and mineralogy. He was elected a fellow of the Linnean Society in 1818 and the following year a fellow of the Geological Society of London. During a geological tour of the Isle of Wight he and Adam Sedgwick engaged in discussions that later led to the formation of the Cambridge Philosophical Society, of which Henslow was a founder. His paper on the geology of Anglesea, prepared after an extensive survey of the island in 1821, was hailed as an important contribution. In 1822 he was elected to the chair of mineralogy at Cambridge.

The professorship of botany at Cambridge, to which Henslow had looked forward for many years, fell vacant in 1825. He immediately offered himself as a candidate for the position and was elected unopposed. Soon after, he resigned his chair of mineralogy and devoted himself completely to the study and teaching of botany. Systematic botany did not appeal to him; he considered it necessary only so far as it helped the study of the distribution of plants. His main interests were plant geography, morphology, and physiology. He organized botanical excursions, encouraging students to observe and study plants in their natural environment. He used his own diagrams and actual specimens at lectures to demonstrate form and structure in plants. He required students to disse, examine, and describe the specimens they were studying. Under Henslow botany became one of the most popular subjects at Cambridge; among his students were Charles Darwin, Berkeley, R. T. Lowe, W. H. Miller, Babington, and others. Henslow recommended Darwin as naturalist for H. M S. Beagle and during the five-year voyage regularly corresponded with Darwin and took care of all specimens sent by him.

Henslow’s persistent efforts eventually resulted in the redevelopment of the long neglected Cambridge Botanical Garden, which he regarded as an essential adjunct to the teaching of botany. He always maintained a lively interest in museums and was directly responsible for, or contributed freely toward, their establishment in Ipswich, Cambridge, and Kew. For a number of years Henslow was a member of the senate and an examiner in botany at the University of London. He was also an active founder-member of the British Association, presiding over its natural history section on many occasions.

Henslow was ordained in 1824 and became curate of Little St. Mary’s Church in Cambridge. He was appointed vicar of Cholsey in Berkshire in 1833. Four years later he received from the crown the rectory at Hitcham in Suffolk, where he moved in 1839 and resided until the end of his life. He went to Cambridge every year to deliver his lectures and he taught botany and horticulture to village children in his parish school.

In 1823 Henslow married Harriet Jenyns, daughter of the Reverend George Jenyns of Bottisham in Cambridgeshire; they had two sons and three daughters. His daughter Frances was the first wife of J. D. Hooker.

BIBLIOGRAPHY

I. Original Works. Among Henslow’s most important works are “Geological Description of Anglesea,” in Transactions of the Cambridge Philosophical Society, 1 (1822), 359–452; A Catalogue of British Plants (Cambridge, 1829; 2nd ed., 1835); Principles of Descriptive and Physiological Botany (London, 1835); and Dictionary of Botanical Terms (London, 1857).

II. Secondary Literature. A chronological list of Henslow’s publications is given in a full length biography, L. Jenyns, Memoir of the Rev. John Stevens Henslow (London, 1862). A shorter list is in the Royal Society, Catalogue of Scientific Papers, 3 (1869). Other biographical accounts are “The Rev. Professor Henslow,” in Gardener’s Chronicle and Agricultural Gazette (1861), pp. 505–506, 527–528, 551–552; F. W. Oliver, ed., Makers of British Botany (London, 1913); J. R. Green, History of Botany in the United Kingdom (London, 1914); J. Britten and G. S. Boulger, A Biographical Index of Deceased British and Irish Botanists, 2nd ed. (London, 1931); and N. Barlow, ed., Darwin and Henslow; The Growth of an Idea. Letters 1831–1860 (London, 1967).

M. V. Mathew