Sarracenia (trumpet pitcher-plants) and Darlingtonia californica (the California pitcher-plant; Darlingtonia is a monospecific genus) are insectivorous plants. Hooker had evidently found that they were not heliotropic (see letter from J. D. Hooker, 2 October 1879 and n. 4). ‘Light & sweetness’: an ironic reference to the idiom ‘sweetness and light’, popularised by Matthew Arnold’sCulture and anarchy (Arnold 1869).