Cambridge offers botany course that inspired Darwin after rare archive uncovered | Plants

Plant specimens and teaching materials that inspired Charles Darwin and qualified him to work as a naturalist on HMS Beagle have been discovered in a Cambridge archive and will be used for the first time to teach botany to contemporary students.

The fragile specimens, ink drawings and watercolor illustrations of plants belonged to Darwin’s teacher and mentor, Professor John Stevens Henslow, and have been held in the University of Cambridge Herbarium for almost 200 years.

Some of the “very rare” watercolors and drawings, first published in the Guardian, are believed to be the first botanical illustrations Henslow produced to teach his students. Others are specimens of plants that Darwin would have seen for himself.

“When Darwin arrived at Cambridge, he studied botany formally for the first time. He enjoyed Henslow’s course so much that he took it three years in a row,” said Dr Raphaella Hull, Acting Head of Learning at the University of Cambridge Botanic Garden (CUBG). “Henslow introduced him to the concept of variation, thus laying the foundation for Darwin’s later theory of evolution.”

As an Anglican clergyman and natural theologian, Henslow believed that the study of plants could reveal the wisdom of God and the closely observed variations within plant species as he sought to document the infinite breadth, usefulness, and magnificence of God’s creation.

He collected the specimens and designed the illustrations so that he could begin offering Cambridge undergraduates an annual course in botany in 1827.

When Darwin arrived at Cambridge in 1828, he became one of the first students to take Henslow’s revolutionary five-week course. Darwin already had an interest in the natural world, piqued by a natural history group he joined while studying medicine at the University of Edinburgh. But he had abandoned the course after two years, realizing he did not want to follow in his father’s footsteps to become a doctor and instead heading to Cambridge with the intention of becoming a clergyman.

Henslow took Darwin and his comrades on “herbal excursions” to the marshes of Cambridgeshire and taught them to identify, categorize and collect plants, while systematically observing the adaptations of different plant species to their environment.

This was Darwin’s introduction to the scientific study of botany and the insights that the rigorous collection of empirical data could offer about the natural world. He later described Henslow as having “influenced my whole career more than any other”.

“I firmly believe that no better man has ever walked this Earth,” he wrote upon Henslow’s death in 1861.

CUBG is reviving the spirit and content of Henslow’s teaching by launching a four-week summer course in botany aimed at internal and external undergraduate and postgraduate students, academic researchers and professionals working in ecology, horticulture, conservation or related fields.

During the course, students will learn botany using the original teaching materials and practical techniques used by Henslow to teach Darwin in the 1820s, as well as field trips to the types of habitats Darwin visited in the Cambridgeshire countryside.

“Botany has virtually disappeared as a standalone undergraduate degree in the UK, creating a real divide in the way people are trained to understand plants,” said Professor Sam Brockington, curator of CUBG. “Even in plant science labs, we find more and more talented students who lack the language or conceptual framework to describe the form and diversity of plants.”

One of the motivations for creating this course was to fill this gap. “We designed what we considered to be the ideal four-week immersive program in botany, and when we compared it to the program taught by Henslow at Cambridge in the 19th century, the overlap was remarkable. In many ways, we are not only drawing on that tradition, we are bringing to life the spirit of Henslow himself,” Brockington said.

Henslow taught botany in a way that proved deeply popular, Hull said. “It’s the most complete and comprehensive way to teach botany. You have to get your hands on the equipment. You have to go see it in the field… you take the equipment apart, you dissect it, you see its smell, you see it in its natural habitat.”

Today, plant scientists study plant processes at the cellular level, and their work can become very siloed and species-specific, Hull said. “Understanding plant morphology and diversity allows you to place your findings in a broader context. In terms of biodiversity loss and climate change, being able to observe and understand what is around us is essential.”

She noticed that plant science students often feel like they lack species identification skills, but are eager to develop them. “If we don’t have botanists who can analyze the environment and the species in it, we don’t have a good way to understand the state of habitats around the world,” she said.

Records suggest that Darwin was a particularly intrepid student. While attempting to harvest bladderwort for Henslow on a marshy heath, the young naturalist is said to have slipped underwater into a ditch, greatly amusing his comrades – only to emerge shortly afterwards, triumphantly holding the precious aquatic plant.

When the aristocratic captain of the HMS Beagle, Robert Fitzroy, offered Henslow the position of “gentleman naturalist” aboard his ship in 1831, the professor refused and instead recommended the 22-year-old Darwin. Darwin then faithfully mailed the specimens he had collected during his journey to his former tutor and mentor. “They remained friends for the rest of their lives,” Hull said.

Brockington said Henslow’s use of illustrations in his course was pioneering. “He was doing PowerPoint presentations 200 years ago.” He hopes that students who take the new four-week course will feel inspired by the materials and methods Henslow used to teach Darwin. “It’s like standing on the shoulders of giants.”

Before Henslow began teaching his course, no botany course had been taught at Cambridge for decades. “We saw a real gap – and Henslow saw the same gap,” Hull said. “He wondered why scholars did not view botany as the absolute essential stepping stone to greater discoveries. He viewed it as the foundation. We view it as the foundation as well.”