Obituary Patricia Anne Sims (1932-2026)
by David Williams, Eileen Cox and Edgley Cesar |
On the 1st October 1951, Patricia Anne Sims, not yet 19 years old, joined the Botany Department of the British Museum (Natural History), our old name, as ‘temporary scientific assistant’. First assigned to the Pteridophyta section, under the leadership and guidance of A.H.G. Alston (1902–1958) but later transferred to the diatom section, headed up by Robert ‘Bob’ Ross (1912–2005). Initially trained as an ecologist (but already an accomplished botanist specialising in heathers, Ericaeae), Bob Ross joined the NHM in October 1936 as its first dedicated diatom researcher. Before his arrival at the museum, diatom studies and the diatom collections were considered to be, administratively at least, part of algae. Having departed for Africa in 1952 as the botanical member of the Ruwenzori expedition, Ross had insisted that, on his return, there should be an assistant to help him with the diatom collections. George Taylor FRS (1904–1993), then keeper of Botany at the BM, arranged the transfer ushering in the beginning of Pat’s life-long career at the Museum amongst the diatom collections. After 41 years, Pat retired in 1992 (at that time retirement was compulsory at 60), becoming a Scientific Associate, a position she actively held until her death on the 29th May 2026 – her final contribution was published only a few weeks ago (8th May): Williams, D.M., Sims, P. & Ashworth, M.P. (2026). Notes on the diatom collection of the Natural History Museum, London (BM) X: Roper’s species of Biddulphia (Bacillariophyta). Phytotaxa 755(2): 121–153.
By 1966 Ross had become Keeper of Botany (Head of Department) and matters other than diatom systematics took precedence. It was now that Pat was able to drive the understanding of diatom structure and, in a more general sense, the classification of all diatoms. In Ross’s words, having a particular ‘taxonomic problem in mind’ and making an effort to ‘understand the images’ came to the fore with the series of studies notable for their pioneering work with the scanning electron microscope, used as a means to an end, rather than simply another technical advance in microscopy. After a review of species in the genus Aulacodiscus, Pat and Ross produced three papers that broke new ground: examining the ‘Generic limits in the Biddulphiaceae’ (1971), exploring the ‘family and generic limits in the Centrales’ (1974) and, derived from their understanding of various structures, offered the first modern terminological interpretation of ‘the frustule in centric diatoms’ (1972). This was the start of Pat’s investigations of various centric diatom groups with the scanning electron microscope, mostly fossil marine species, in all publishing over 50 papers, around half of those being written after her retirement.
While fossil centric diatoms were clearly Pat’s ‘first-choice’ research programme, with the arrival at the BM of Thomas ‘Barrie’ Barrington Barnes Paddock (1942–) in 1968, appointed to develop a range of approaches using transmission and scanning electron microscopy to examine diatom valves, a new joint research programme began, addressing what was then understood to be the most derived and complex diatom species groups, Epithemiaceae–Surirellaceae. Their efforts together produced 7 papers, all lengthy detailed examinations of various poorly reported valve structures (especially those diatoms with keeled valves), painstakingly teased out from laborious searches for rare specimens to provide interpretations of these complex valve structures. These studies were to dominate Pat’s time until Barrie left the Museum in 1990, when Pat returned to her work on marine fossil diatoms. Pat’s research history, then, is intimately linked with the evolution of electron microscopy, from its discovery as a tool to reveal exceptional details of diatom valves, through to its maturation as a standard, almost compulsory, method of investigation for diatom systematists, not so much surpassing light microscopy, as enhancing it.
Pat produced over 90 publications. Many were detailed monographs, most focused on revisionary taxonomy, and amongst these varied contributions were two books, one in honour of her friend and mentor, Robert Ross, Progress in diatom studies. Contributions to taxonomy, ecology and nomenclature. In honour of R. Ross, and the second, another labour of love, a guide to British diatoms, An Atlas of British Diatoms. A third book, A Handbook of Cretaceous Diatoms, for Cambridge University Press, is not yet finished but due for completion early 2027.
In aggregate, Pat was responsible for over 300 taxonomic acts, which included the description of well over 40 new fossil diatom genera and countless numbers of species, all derived from a variety of unstudied fossil deposits. None of this would have been possible without her keen sense of the value of specimen collections and their active study and curation. Pat’s legacy, then, is not just the published results, but the specimen collection preserved in our museum for future researchers.
Pat was also a founder member, and first treasurer, of the International Society for Diatom Research, as well as a regular participant in the more informal British Diatomists’ Meetings. In both, her involvement underlined her appreciation of the value of collaborative interactions with other diatomists. She was always welcoming to visitors, both established researchers and students, encouraging the use of the collections and willing to discuss ideas.
For her 80th birthday, Pat’s work was celebrated with the publication of a festschrift: Witkowski, J., Williams, D.M. & Kociolek, J.P. (eds), Diatoms and the continuing relevance of morphology to studies on taxonomy, systematics and biogeography. Celebrating the work and impact of Patricia A. Sims on the occasion of her 80th birthday (Nova Hedwigia, Beiheft 144, 2015).
This account is based on Williams, DM. & Hasle, G. 2015. Pat Sims: A bibliography with annotations concerning type material. in the festschrift listed above. If anyone wants a copy of the Williams & Hasle account, please drop DMW a line (d.m.williams@nhm.ac.uk).