John Stevens Henslow accepted the Chair of Botany in 1825 at a time that the study of botany was at a very low ebb in the University. It had suffered from the absenteeism from Cambridge of his predecessor [Thomas Martyn] for 30 years. No lectures had been given during this long period, and the Botanic Garden in the center of the city was struggling. The young and vigorous Henslow came to his post with a very different perspective.
He took a degree in mathematics at St John’s, had been a natural historian from boyhood, studied the new disciplines of geology and mineralogy from undergraduate days, and had been a demonstrator for the chemistry practical classes of Professor James Cumming. Henslow was a polymath indeed. In 1823 at the age of 27, he succeeded Edward Clarke as Professor of Mineralogy. Two years later he accepted the Chair of Botany too.
Henslow inherited few botanical resources in 1825: the herbarium was rapidly decaying, and the Botanic Garden was unfit for his novel purposes. These purposes were clear: to provide a plant collection and facilities for a modern experimental approach to botany, not just drug plants for the education of medical students.
Botany was a serious experimental science, taking its rightful place in the upsurge of enthusiasm for the natural sciences which characterized Cambridge in the early 19th century. Henslow was a leading light in the academic community, founding, for example, the Cambridge Philosophical Society with Professor of Geology, Adam Sedgwick. To this day, the Society acts as a forum for debate and dissemination of knowledge concerning the natural sciences and mathematics.
As a new professor, Henslow threw himself into botany, planning his lecture course, gathering together a massive herbarium of British plants for research and beginning the debate for the new Botanic Garden. A new Garden must offer all types of plants for experimental botany – trees as well as herbs – requiring a much larger area for their growth than could be found in the city center.
As you walk around the Western half of the Botanic Garden you are experiencing and enjoying the Botanic Garden of John Stevens Henslow (left and below holding a Herbarium Sheet). His intellectual vision, political skills, humanity, and persistence brought the Garden into being, and we have been left with a priceless treasure. In 1830, n 1830, the University commissioned a botanic garden plan for this entire area of about 40 acres from an architect working locally, Edward Lappidge.
This plan shows the elements we are still familiar with – a lake, a complex of systematic beds, a formal lawn, glasshouses – all set within an envelope of trees. An 1831 Act of Parliament transferred title from Trinity Hall to the University, so all was set for development. Just before signing the release for his tenancy, however, Rev Bullen died and his widow was persuaded by her son-in-law to hold out for a better cash settlement of the remaining years of the tenancy. The University was unable (or unwilling) to offer more, and so development was delayed for 13 years until the lease expired.