English botanist from Paddington, London who was Assistant in the Department of Botany at the British Museum (1869-1879) and published a local flora of Middlesex (1869) with W.T.T. Dyer, later publishing on medicinal plants with R. Bentley (1875-1880). He was subsequently appointed Director of the Botanic Gardens at Peradeniya (1879-) in Ceylon (Sri Lanka) where he developed a Museum of Economic Botany and opened branches of the gardens at Badulla and Anuradhapura. Trimen began a flora of Ceylon (1893-) but this was not completed until after his death by J.D. Hooker. The genus Trimenia Seem. in the Monimiaceae was named in his honour, but this genus is sometimes treated as belonging to a separate family, the Trimeniaceae. Original British collections of Trimen are at BM, his herbarium of some 3,000 vascular plants received in 1873. Material from Sri Lanka is mainly at PDA and K.