Albert Oliver Dean Mogg, botanist, was the son of Joseph William Mogg, estate owner of Pretoria, and his wife Agnes Emma Johanna, born Krause. After receiving his schooling at St Andrew's College, Grahamstown, he attended the Merchant Venturer's Technical College in Bristol, England. Thereafter he received some training during 1907-1908 at the Potchefstroom Agricultural Experimental Farm (from 1909 the Potchefstroom Agricultural School and Experimental Farm). In the latter year he received a government agricultural scholarship to continue his studies at the Ontario Agricultural College at Guelph, Canada, during 1908-1909. He then entered Gonville and Caius College at the University of Cambridge, England, where he graduated as Bachelor of Arts (BA) in 1913.
Upon his return to South Africa that same year Mogg was appointed as assistant botanist in the Department of Agriculture, a post he held until 1917. When World War I (1914-1918) broke out he went on active service as a staff lieutenant in the German South West Africa (now Namibia) campaign of 1914-1915. From 1917 to 1927 he worked as botanical research officer (from 1922 senior research officer) and lecturer in ecology in the Division of Veterinary Services of the Department of Agriculture in Pretoria. He continued his studies at the Transvaal University College, Pretoria (later the University of Pretoria), qualifying as Bachelor of Science (BSc) in 1921. The next year the University of Cambridge awarded him the degree Master of Arts (MA).
In 1927 Mogg was appointed as a botanist in the Division of Plant Industry (later the Division of Botany and Plant Pathology), where he remained to his retirement in 1946, except for military duty in the Medical Corps in Egypt during World War II (1939-1945). While on secondment to the Onderstepoort Veterinary Research Institute during the late nineteen-twenties he continued the research on vlei poisoning that had been interrupted by the death of C.P. Neser* in 1929. At that time he collected plants in KwaZulu-Natal, East Griqualand, at Vryburg and around Pretoria. At the Fifteenth International Geological Congress held in Pretoria in 1929 he contributed two papers, on the flora of the Vryburg District and Pretoria District respectively, in relation to the geology. Both papers were included in the Comptes Rendus published after the congress. His other publications included several papers in the South African Journal of Science, on a method of veld estimation (1920), vlei poisoning (1927), the poisonous 'Gifblaar' (Dichapetalum cymosum) (1930), and 'Steekgras' in relation to the sheep industry (1934).
Mogg was interested also in archaeology and, as co-author of E.C. Chubb* and G.B. King, contributed to a 'Preliminary report upon a variation of Smithfield Culture from a cave on the Pondoland coast' (South African Journal of Science, 1933, Vol. 30, pp. 550-551). The next year the same authors published a more comprehensive account of the same finds in the Transactions of the Royal Society of South Africa (1934, Vol. 22(4), pp. 245-267).
After his retirement Mogg lectured in botany, crop production, horticulture and forestry in the Soil Conservation Faculty of the University of the Witwatersrand until 1954. Subsequently he became curator of the university's Moss Herbarium (1956-1959) and continued working there for a few more years. In 1961 he qualified as Doctor of Philosophy (PhD) at the University of the Witwatersrand with a thesis titled The trees, shrubs and woody herbs of the Witwatersrand region in relation to the geology and physiography. In 1975 he published Important plants of Sterkfontein: An illustrative guide (University of the Witwatersrand, 1975).
Mogg became a member of the South African Association for the Advancement of Science in 1915, served as joint secretary of Section C (which included botany) at the association's annual meetings in Caledon (1930) and Grahamstown (1931), and was a member of council from 1949 to 1965. He also served as vice-president of the Tree Society of South Africa for many years. During his long career he collected some 40 000 plant specimens throughout South Africa, but also in Southern Rhodesia (now Zimbabwe) and southern Mozambique. Many of his specimens went to the National Herbarium in Pretoria, the Moss Herbarium, the herbarium of the Royal Botanical Gardens at Kew, England, and the herbarium of the Natural History Museum, London. The species Moraea moggii, Eragrostis moggii, and Combretum moggii were named in his honour.