Her father Harry, orphaned as an infant, was a naturalist and had long been interested in paleontology, and frequently went searching for fossils, plants, and insects.
[citation needed] Between 1870 and 1880, Jelly sent a series of letters to the botanist Edward Adolphus Holmes, five of which are preserved in the archives of the Linnean Society of London.
In 1870 she discussed the moss Dicranella fallax (Wilson, 1870) that she had found in "a deep[-]ish ditch, down close to the water & hidden by grass".
Holmes had also sent her samples of an unidentified zoophytes, which she returned them to him, saying that she was unable to identify one of them as it did not belong to any of the families she was studying, suggesting her mastery with seaweeds, algae, lichen, and mosses.
She and her long time friend, Edith Williams, with whom she lived for many years, were buried together in a double grave in the Chart Lane cemetery of Reigate in Surrey.