Botanist and gardener. Born in Aberdeen, Masson moved to London in the 1760s to work as an under-gardener in Kew Gardens. The notable botanist Sir Joseph Banks sent Masson on a plant-collecting expedition to South Africa (1772-75), sailing with Captain James Cook to Cape Town on board HMS Resolution. He returned with more than 500 plant species, with his introductions including varieties of Gardenia, Gladioli, Lobelia, Pelargonium, Protea and Strelitzia regina, the Bird of Paradise flower. He was celebrated as Kew's first plant-collector and his reputation assured. Further expeditions followed; Madeira, Canary Islands, the Azores and the Antilles (1776), Portugal (1783) and a return-trip to South Africa (1786-95), publishing Stapeliae Novae on South African succulents the following year. His final expedition was to North American in 1797, where he travelled overland from New York to the Great Lakes, collecting plants and seeds as he went. He died in Montreal and is buried there.
The genus of plants Massonia is named in his honour and he is remembered at the Scottish Plant Hunter's Garden (Pitlochry) and by a plaque in Cruickshank Botanical Gardens (Aberdeen).