[a] Despite not having any family background in science (though he recalled that his grandfather was the university rat-catcher)[5] he developed a keen interest in natural history and books at an early age.

He spent his school holidays on his uncle's Suffolk farm, tending cows grazing by the roadside where he would observe the wildflowers of the hedgerows and fields.

[12] Seward was impressed by the young Stearn, giving him access to the herbarium of the Botany School (now Department of Plant Sciences—see 1904 photograph) and allowing him to work there as a part-time research assistant.

[22] He was described as having a striking figure, "a small man, his pink face topped with a thatch of white hair",[9] and earned the nickname of "Wumpty" after his signature of "Wm.

In addition to Professor Seward, those influencing him included the morphologist Agnes Arber, Humphrey Gilbert-Carter the first scientific director of the Botanic Garden, John Gilmour then curator of the university herbarium and later director of the Garden (1951–1973), the horticulturalist E. A. Bowles (1865–1954), who became his patron,[15] Harry Godwin, then a research fellow and later professor and Tom Tutin who was working with Seward at that time.

As a conscientious objector, he could not serve in a combatant role, but was accepted into the Royal Air Force (RAF) Medical Services, as he had previously worked with the St John Ambulance Brigade.

[9][12] From the Lindley Library, Stearn (see 1950 Photograph) moved to the Botany Department at the Natural History Museum, South Kensington[f] in 1952, and by the time he retired in 1976, he was the Senior Principal Scientific Officer there.

[5] He continued to travel widely, with field work in Europe (particularly Greece), Australia, and the United States,[9] and published 200 papers during his 24 years at the museum, and although the library was not his responsibility, he spent much time there adding written notes to many of the critical texts.

[23] He continued his association with the Lindley Library all his life, being an active committee member[9] and regularly attended RHS flower shows even after he was barely able to walk.

[13][58] He was a liberal contributor to the journal, and during this time he and Eldwyth Ruth Stearn undertook their translation of The Greek Plant World in Myth, Art, and Literature (1993).

Stearn became a member of the Botanical Society of Britain and Ireland (BSBI) in 1954,[62] joining the Maps Committee the following year to prepare their Atlas of the British Flora (1962).

[56][l] This text, in an expanded and revised edition, as Woodcock and Stearn's Lilies of the World (1950)[90] became a standard work on the Liliaceae sensu lato.

While his genus monographs largely concentrated on Mediterranean flora, notably Epimedium,[82] Allium[95][96] and Paeonia,[97] he was also the author of species articles both popular and technical as well as a number of classical treatises.

[107] Stearn compiled a major work on the life of John Lindley[36] and produced an edited version of the classic book on herbals by Agnes Arber,[111] one of the influences of his Cambridge years, and whose obituary he would later write for The Times.

[116]Stearn's historical research is best known for his work on Carl Linnaeus (1707–1778), which he began while at the Natural History Museum, and which won him a number of awards at home and abroad.

[47][117][118] Of Stearn's writings on Linnaeus, the most well known is his edition of the 1753 Species plantarum, published in facsimile by the Ray Society in 1957,[119] for which he wrote both a 176-page introduction and an appendix.

The Times stated that no other botanist possessed the historical knowledge and linguistic skills to write, what is considered one of the classic studies of the Swedish naturalist and a highpoint of 20th century botanical scholarship.

[1][7][127] Although Stearn spent much of his life studying and writing about Linnaeus, he did not admire the man's character, describing him as mean—"a jealous egoist, with a driving ambition".

Cultivar, a term first proposed by L. H. Bailey in 1923,[133] refers to a distinctive genus or species variety raised or maintained in cultivation, such as Euphorbia dulcis "Chameleon".

[5] Stearn continued to play an active part in the International Botanical Congresses over many years, where he was remembered for his rhetorical persuasion on nomenclatural matters.

[15][135] Motivated by his interest in botanical history and taxonomy, Stearn devoted a considerable part of his output to botanical bibliography, including numerous papers and catalogues establishing the exact publication dates of books on natural history, particularly from the early nineteenth century, including William Herbert's work on Amaryllidaceae (1821, 1837)[131][8][136] and complete bibliographies of botanists such as John Gilmour (1989).

[137] At the RHS library he transformed the minimalist card indexing by introducing British Museum rules and adding extensive bibliographic information.

[12] He considered his most important contribution in this regard to be his elucidation[138] of the dating of the early 19th century collection of studies of Canary Islands flora by Webb and Berthelot (1836–1850).

[139] Another important work from this period was on Ventenat's Jardin de la Malmaison (1803–1804), also published in the new Journal of the Society for the Bibliography of Natural History.

[140][12] In a number of instances his contributions to others' work went unacknowledged, particularly when he was younger, even though his introductions (often with the title "Revised and enlarged by W. T. Stearn") could be as lengthy as the texts they preceded.

[141][v] His contributions to botanical bibliography and in particular the correct interpretation of historical texts from Linnaeus to Arber are considered of central importance to the field of taxonomy.

[7][12] His continuing interest in botanical illustration led him to produce work on both historical[147] and contemporary artists,[148][149] including the Florilegium of Captain Cook and Joseph Banks from their first voyage (1768–1771) to the Pacific on the Endeavour,[150] the similar account of Ferdinand Bauer's later botanical expedition to Australia with Matthew Flinders on the Investigator (1801–1803),[151] and the work of illustrator Franz Bauer (the brother of Ferdinand).

[21]Stearn is considered a preeminent British botanist, and was once likened to botanical scholars such as Robert Brown, Darwin, the Hookers (William and Joseph) and Frans Stafleu.

[11] On his death, The Times noted his encyclopedic grasp of his field, stating that he was "acknowledged as the greatest botanical authority of the twentieth century".

[168] His contribution to his field was far greater than his extensive bibliography suggests, since he was known for his input into many of his colleagues' work, leading Professor P. B. Tomlinson to observe "he left no tome unstearned".