Carnivorous Plants - Down House and Cambridge

Like many areas of evolutionary biology, it’s almost impossible to think about the origins of our study of these plants without turning to Darwin. The publication of his book Insectivorous Plants in 1875 saw the birth of carnivorous plant biology as we understand it today. Criticisms by prominent authorities on botany (i.e. Linneaus) had led to many accounts of plant carnivory being largely dismissed by European scholars. Like most scientists that come into contact with these plants, Darwin was enthralled. After encountering the Venus fly-trap he proclaimed it to be “one of the most wonderful plants in the world.” I explored Darwin’s study of these plants by visiting two sites closely associated with him: Down House (where most of the work that went into Insectivorous Plants took place) and Cambridge University (home of the Darwin Correspondence Project and Christ's College, where Darwin studied as a young man).

Down House - The Darwin family home.

The trip to Downe from central London was a pretty straightforward train and bus ride away. Public transportation has been way more convenient than Boston, in my opinion, and I was lucky enough to enjoy clear blue skies on the trip after an overcast first few days. Before making the short walk from the small bus station to the Darwin family home I wandered around the nearby St. Mary’s church and cemetery, where I found the graves of Darwin’s wife, Emma, along with several of his children and a modest memorial to the man himself. I later found out that Darwin had wished to be buried there, but instead rests in Westminster Abbey at the request of his countrymen. I attended mass at Westminster the following Sunday to check it out.

Specimens from Darwin's work.

The house itself is picturesquely nestled in the countryside, and after entering I took a self-guided audio tour of the estate. Now a property of the English Heritage charity, the house is an eclectic combination of preservation efforts to keep it as similar as possible to its original living conditions, and museum exhibits displaying Darwin manuscripts and family artifacts alongside information on the history of biology.

We know from his correspondence with Hooker at Kew that Darwin’s interest in this peculiar realm of botany began as early as 1860. Darwin’s ”kitchen-sink” style experiments were carried out almost exclusively in his home and personal greenhouse in Down. With an ample indigenous supply, he focused mainly on Drosera rotundifolia. However, the greenhouse now contains a plethora of carnivorous plants from around the world. I was unable to meet with the greenhouse curator, Ray Heaton, in person. But after my visit, we set up a phone call and discussed his decisions to mix the plants Darwin focused on (Sundews - Drosera, Venus Fly-trap - Dionaea muscipula, and bladderworts - Utricularia) alongside many more popular species (like the pitcher plants Nepenthes, Sarracenia, and Cephalotus) to enhance the educational value of the space, and to make it more engaging for visitors. His work with the estate also focuses on recreating some of Darwin’s more DIY experiments for visiting groups, and we even discussed the potential of recreating some of the work with sundews that went into Insectivorous Plants.

Darwin's personal greenhouse.

Following the publication of Insectivorous Plants, there was an explosion of scientific excitement and experimentation with various species. Some of which had been described centuries ago and the nature of their appetites had simply been overlooked, while others were relatively new to European eyes. Darwin certainly didn’t know everything about these plants, but with the use of modern techniques and continued interest in plant carnivory across the scientific community, we now know that many of his speculations have been proven true. His work laid the theoretical foundations for modern botanists to explore these fascinating organisms with technological innovations only now becoming available (genome sequencing, electron microscopes, etc).

Sarracenia display at Cambridge.

After my day in Downe I hopped on a bus up to Cambridge, where I spent some time exploring the Cambridge University Botanic Gardens, the university library’s extensive rare books collection (also home to most of Darwin’s correspondence), and the many historic sites that make up the campus. It was on a slightly overcast but otherwise pleasant day that I went to check out the botanic gardens. Although not quite as exciting as Kew Gardens, which I’ll be talking about in my next post, they are an incredibly peaceful place to spend an afternoon, read a book, and eat a sandwich on a park bench (which is the bulk of what I did). Which pretty much sums up my wanderings there. I was especially excited to find a modest collection of carnivorous plants at the entrance to their greenhouse, which despite ongoing renovations housed some gorgeous tropical species of Nepenthes pictured here.

Nepenthes

The first illustration of a Venus Fly-Trap.

From there it was a short walk to the university library, where I obtained a reader’s card and dove into some of my materials. I was most excited to find John Ellis’ published letter to Linnaeus including the first known illustrated description of the Venus Fly-trap, connecting back to the Ellis letters I had found at the Linnaean Society. Additionally, the bulk of Darwin’s correspondence on insectivorous plants is kept here and can be accessed online through the Darwin Correspondence Project: https://www.darwinproject.ac.uk/insectivorous-plants-0

The letters cover Darwin’s communications with a broad range of actors in this 15-year-long saga of blood, sweat, and tears (most of which were fed to his precious plants at one point or another). This cast includes his long-time friend Joseph Dalton Hooker at Kew Gardens, geologist Charles Lyell, and the American botanist Asa Gray at Harvard. His language throughout the letters reveals a man absolutely devoted to the topic at hand. Despite taking several extensive breaks from his work due to both personal and family health problems, he never stopped using glowing language about his work with Drosera. To be fair, he took this approach with many of his projects at Down House, including nearly a decade spent with his “beloved barnacles.” Like most of his post-origins work, I found that he was especially fascinated with seeing how carnivorous plants are related to one another, and how the accumulation of many small adaptations over time created bizarrely specialized organisms that perfectly illustrate his theory of evolution by natural selection. If you’d care to dive deeper into Darwin’s own words about these plants, here’s a song composed from his real letter excerpts: https://vimeo.com/316587632

Cambridge University Library Card (so official!)

Before heading back to London I spent some time wandering the campuses and occasionally pretending to be a prospective student to gain access to university buildings; almost stumbling into a graduation ceremony at King’s College (along with several reunions and choir practice). Although not directly related to my trip, I also stopped by the university art and antiquities collection at the Fitzwilliam Museum. All things considered, this was a fruitful leg of my journey and a welcome break from the hustle and bustle of the city!

King's College, University of Cambridge