Harry Howard Barton Allan was born in Nelson on 27 April 1882, the youngest of six children of Emma Maria Lewis and her husband, Robert Allan, a clothier. Harry attended the local Boys’ Central School, where the headmaster, F. G. Gibbs, introduced him to botany. He then won a scholarship to Nelson College, where he received prizes for literature and athletics and began a BA. From 1903 he taught at a succession of schools, while continuing part-time university study. In 1907 he obtained a position at Waitaki Boys’ High School in Oamaru, and graduated MA at Auckland University College the following year. On 7 September 1909 at Motupiko, near Nelson, he married Hannah Louise Arnold; they were to have a son and a daughter.
At Waitaki the new rector, Frank Milner, was reinvigorating the school. There had been pressure on secondary schools from the Department of Education to provide more practical subjects in addition to the traditional Classics, and when Milner accordingly planned an agricultural course, Allan’s interest in botany was put to use. He was soon teaching the entire course. He made contact with A. H. Cockayne of the Department of Agriculture, Industries and Commerce and organised experimental work at the school. Some of the results were published in the Journal of Agriculture in 1913.
In 1916 Allan left Waitaki to become the agriculture master at Ashburton High School, and to assume responsibility for the experimental farm being established there in association with the department. But contacts with the notable botanist Leonard Cockayne (A. H. Cockayne’s father) had turned Allan’s interest more towards botany than agriculture, even though it was mainly a spare-time pursuit which seemed to offer fewer prospects. There were some rewards: Cockayne supported his election as a fellow of the Linnean Society of London in November that year and encouraged him in his lengthy botanical study of Mt Peel in Canterbury. When he submitted this as his doctoral thesis he acknowledged his debt to Cockayne, describing him as ‘my friend and master’.
On graduating DSc in 1923 Harry Allan moved again, becoming English master and first assistant to another notable principal, L. J. Wild, at the newly established Feilding Agricultural High School. However, he continued with his botanical research, working late into the night. By the mid 1920s he had become an important collaborator for Cockayne, especially in the latter’s work on hybridisation between species; Allan provided the experimental proof, crossing plants artificially and growing the resulting hybrids in his school and home gardens. He also found time to write a popular book, New Zealand trees and shrubs and how to identify them (1928).
Allan was stimulated and extended by his work with Cockayne and by meeting the leading overseas botanists who came to visit him. He also gained recognition as a botanist in his own right. In 1927 the Royal Society of London made him a grant for his studies, and in the following year he was elected a fellow of the New Zealand Institute (later the Royal Society of New Zealand). With the development of organised science in New Zealand he was finally able to leave teaching and became a professional botanist: in 1928 he was appointed to the new Plant Research Station in Palmerston North.
Allan began studies in economic botany (on grasses and weeds), steering clear of the factional disputes between scientists, and the power struggles between departments, which divided the station. In 1936, when the DSIR gained control of the station and split it up, he became the head of the Botany Section (later Division), located from 1937 in Wellington.
With Cockayne’s death in 1934 Allan had emerged as New Zealand’s foremost botanist. Over the next decade he built up his division as the main botanical research group in the country. Despite his quiet, retiring nature he also became a leading figure in local science. The Royal Society of New Zealand awarded him its Hutton Memorial Medal in 1941 and the Hector Memorial Medal and Prize in 1942. He became vice president of the society in 1941 and served as president from 1943 to 1946. On an international level, he was a member of the Swedish Phytogeographical Society and the Göteborg Royal Society of Arts and Sciences. In 1957 he received an honorary PhD and MA from Uppsala university, Sweden.
In 1948 Harry Allan formally retired as the director of the Botany Division and was made a CBE for his services. He gladly relinquished his administrative duties to turn to the culminating work of his career: a new systematic treatise on the plants of New Zealand. He worked methodically through the native dicotyledons, conifers and ferns, assisted from 1953 by Lucy B. Moore, but by 1957 his health had failed. He died at Wellington on 29 October, survived by his wife and children.
Although he had driven himself to the end, his work was not quite finished. Moore completed it for publication in 1961 as volume one of the comprehensive Flora of New Zealand. It became the standard work on the subject; a lasting achievement of this painstaking, shy and modest man.