He was also a constant supporter of the S.Afr.Assoc. for the Adv. of Science, contributing regularly to their journal. Attending one of their meetings in Rhodesia in 1920, he suffered stroke which left him partially paralysed, but despite the handicap, continued with his work. He relinquished all his business interests and devoted all his time to finishing his opus magnum, a comprehensive study of trees in Southern Africa up to the Zambesi and Cunene Rivers. Death intervened and the unfinished manuscript is still kept at the National Botanical Research Institute in Pretoria, which also houses his library. Sim is commemorated in Simia, a genus of liverworts and numerous specific names. Thomas Robertson Sim should not be confused with the agronomist James Taylor Robertson Sim (1903–1968), who was the son of TR Sim's brother, James Sim, also for many years a forestry officer. This botanist is denoted by the author abbreviation Sim when citing a botanical name. Publications Handbook of the Ferns of Kaffraria (Aberdeen 1891) The Ferns of South Africa (Cape Town 1892) Sketch and Checklist of the Flora of Kaffraria (Cape Town 1894) Botanical Observations on the Forests of Eastern Pondoland Recent Information concerning South African Ferns and their distribution (1906) The Forests and Forest Flora of the Colony of the Cape of Good Hope (Taylor & Henderson, Aberdeen 1907) Forest Flora and Forest Resources of Portuguese East Africa (Aberdeen 1909) The Ferns of South Africa (enlarged 2nd edition) (Cambridge 1915) Handbook of the Bryophyta of South Africa (1916) Flowering Trees and Shrubs for use in South Africa (Dept of Mines & Industries Mem No.3 Pretoria 1921) The Bryophyta of South Africa (Trans. Roy. Soc. S.Afr. 1926) Tree-planting in South Africa (Pietermaritzburg 1927) Tree-planting in Natal Sources Botanical Exploration of Southern Africa Mary Gunn & LE Codd (Balkema 1981) 1858 births Botanists with author abbreviations Harvard University staff 20th-century South African botanists Bryologists Fellows of the Linnean Society of London Fellows of the Royal Horticultural Society Fellows of the Royal Society of South Africa Alumni of the University of Aberdeen 1938 deaths People from Aberdeenshire People from Qonce South African foresters British foresters 19th-century South African botanists