James (Jacobus) J. Dickson (1738–1822) was a Scottish nurseryman, plant collector, botanist and mycologist. Between 1785 and 1801 he published his Fasciculus plantarum cryptogamicarum Britanniae, a four-volume work in which he published over 400 species of algae and fungi that occur in the British Isles. He is also the author of Collection of Dried Plants, Named on the Authority of the Linnaean Herbarium and Other Original Collections. The plant genus Dicksonia is named after him.
He was born at Kirke House, Traquair, Peeblesshire, of poor parents, and began life in the gardens of Earl Traquair. While still young he went to Jeffery's nursery-garden at Brompton, and in 1772 started in business for himself in Covent Garden.
Dickson made several tours in the Scottish Highlands in search of plants between 1785 and 1791, that of 1789 being in company with Mungo Park, whose sister became his second wife.