Despite never receiving a formal education in botany,[1] he became an eminent scientist, publishing over 100 scientific papers, three introductory handbooks on New Zealand plants, and completing the first volume of a flora in his lifetime.He later taught at King's College, in Auckland, as well as in Napier, before receiving a posting at Waitaki Boys' High School (Oamaru) in March 1907, as the "fourth assistant residential master.[2] In the introduction he writes: "I am deeply indebted to my friend and master, Dr. L. Cockayne, [...] for his unfailing interest and encouragement in all my botanical work, and for his help and criticism during the investigation.[3] Biographer Ross Galbreath describes his focus on economic botany as being what allowed him to avoid the "factional disputes between scientists", which consumed the Research Station at the time.[2] Through artificial selection of grasses, the Plant Research Station made the "grassland revolution", the turning of large areas of New Zealand to pasture, possible.[23] In 1930 Allan was made head of the botany section of the Australasian Association for the Advancement of Science and was sponsored by the Empire Marketing Board to travel to London.[3][24] He attended the fifth International Botanical Congress, held that year in Cambridge, representing the New Zealand Institute, D.S.I.R, the State Forestry Service and the Research Station where he worked.Allan also gave a talk at the Linnean Society, where he formally received his fellowship,[3][25] and attended a conference of the British Science Association in Bristol.[3][33] He travelled to London again in 1950 to view herbarium specimens held at Kew Gardens, also attending the seventh International Botanical Congress in Sweden, and visiting Lapland with lichenologist Gustaf Einar Du Rietz.[3] When the laurel wreath was held high and the words “Harry Howard Allan, absens” were spoken, accompanied by gunfire, our thoughts went to his sick-bed at the other end of the world.First, his understanding of the importance of wild plant hybrids, both in botany, in it which progressed the idea of introgression,[3] and to the New Zealand flora, in whose ecology they play a key role."[1][3] Flora of New Zealand, described by The Nelson Mail as a "botanical bible",[38] is the "standard work on the subject"; the first volume contains descriptions and keys of 116 families, 290 genera, 1457 species, and 272 varieties.[47] After Allan's health began to decline, he was awarded the honorary degree of Doctor of Philosophy and Master of Arts in the University of Uppsala in May 1957, on the 250th anniversary of Carl Linnaeus's birth.
Celmisia allanii
, described in 1935, was named after Allan.
[
42
]