- All botanical illustrations provided by Oak Spring Garden Foundation, Upperville, Virginia.
- All of Darwin’s original woodcut illustrations provided by the Mertz Library of The New York Botanical Garden.
- 1, Photo of Charles Darwin at age seventy-two on the veranda at Down House, with Parthenocissus twining up the post. Photo taken in 1881 by Messers. Elliot and Fry, published in The Life and Letters of Charles Darwin (1887).
- 2, Down House, Darwin’s home in Kent. Wood engraving by J. R. Brown, courtesy of the Wellcome Collection.
- 3, Darwin’s study at Down House, complete with experimental plants. Wood engraving by A. Haig, courtesy of the Wellcome Collection.
- 4, Darwin in his Greenhouse. Illustrated London News, December 1887.