Arthur Wallis Exell OBE (21 May 1901 in Birmingham – 15 January 1993 in Cheltenham)[1] was initially an assistant and later Deputy Keeper of Botany at the British Museum during the years 1924–1939 and 1950–1962.

[2] A noted cryptographer, taxonomist and phytogeographer, he was notable for his furthering of botanical exploration in tropical and sub-tropical Africa, and was an authority on the family Combretaceae.

[6] His reports on the expedition were published in 1944 as a "Catalogue of the Vascular Plants of S. Tome", which for many years served as the standard reference to the islands' flora.

The expedition also acquainted Exell with the Portuguese botanists Luis Carrisso and Francisco de Ascensão Mendonça of Coimbra University.

[9] Returning to the British Museum (Natural History) in 1950, he founded the 'Association pour l'Etude Taxonomique de la Flore d'Afrique Tropicale' (AETFAT) and started the Flora Zambesiaca project, the flora covering the catchment area of the Zambesi River, which at the time comprised the Federation of Rhodesia and Nyasaland, Bechuanaland, the Caprivi strip and Mozambique.