He went to school at the Unitarian Manse on Claremont Hill, Shrewsbury, with Charles Darwin, who first encouraged him to be interested in plants.
[3] Having been a pupil of John Stevens Henslow, Leighton on his return to his native town deferred ordination in order to draw up a flora of Shropshire.
In 1843 he was ordained deacon and priest, and took on clerical duties in Shrewsbury until 1848, when he resigned his curacy at St Giles' Church,[3] and thenceforward occupied himself entirely with botany.
[2] Leighton suffered from deteriorating eyesight, and soon after 1879 gave up his studies; he donated his collection to the national herbarium at Kew Gardens.
[4] In an 1854 work,[5] Leighton coined the term ardella to refer to the small, spot-like fruiting bodies characteristic of the lichen family Arthoniaceae.