Having received botanical training, Holttum was given the role of assistant director at the
Singapore Botanical Gardens in 1922, with the guidance of
Isaac Henry Burkill. He founded the Malayan Orchid Society (now Orchid Society of South East Asia) in 1928. In 1975 the
British Pteridological Society dedicated an edition of The Fern Gazette to celebrate his Eightieth birthday, and the
Biological Journal of the Linnean Society published eight short addresses about his life. The
Flora Malesiana Bulletin published his autobiography, a bibliography of his publications, and a list of 27 plants dedicated to him. There are at least 23 species of plant named after him, with epithets of
holttumii or
holttumianus. Also in 1924,
Holttumia was published, which is a genus of
fungi in the family
Xylariaceae. Then published in 1964,
Rehia which is a genus of plants in the
grass family. Then in 1964,
Holttumochloa which is a genus of
Malaysian
bamboos also in the Poaceae family and native to the hill forests of
Peninsular Malaysia. He received many awards, including the Gold Medal of the
American Orchid Society (1963), the OSSEA Fellowship from the Orchid Society of South East Asia (1963), and the Linnean Medal from the
Linnean Society (1964). ==Death==