John Stevens Henslow, Professor of Botany at Cambridge. He passed on to Darwin the offer of the position of naturalist on the Beagle voyage and stored his collections until Darwin returned to Cambridge in 1836.

See Darwin's recollection of Henslow here.

See also only in Darwin Online: Nora Barlow, 1967. Darwin and Henslow. Text

See: The Complete Photographs of Darwin