Thomas Meehan had described how the structure of the flowers of Pedicularis canadensis (Canadian lousewort) made self-fertilisation impossible in Meehan 1873; his paper was summarised in Annals and Magazine of Natural History 4th ser. 12 (1873): 497–8. In the Annals, Meehan’s observations were supplemented by those of Thomas George Gentry, who reported observing the flowers being visited by Bombus terrestris and described the process of pollen transfer (see also Gentry 1873). Farrer and CD had corresponded in August 1873 on the floral morphology of Coronilla (see, for example, letter to T. H. Farrer, 14 August 1873).