1. Browne, Janet. 2003. Charles Darwin: A Biography. Vol. 2 of: The Power of Place. Princeton, NJ: Princeton University Press.
2. Chamovitz, Daniel. 2012. What a Plant Knows: A Field Guide to the Senses. Melbourne: Scribe.
3. Darwin, Charles R. 1859. On the Origin of Species by Means of Natural Selection. London: Murray.
4. Darwin, Charles R. 1862. On the Various Contrivances by Which British and Foreign Orchids are Fertilised by Insects, and on the Good Effects of Intercrossing. London: John Murray.
5. On the Movements and Habits of Climbing Plants.