R. H. Richens was the Director of the Commonwealth Bureau of Plant Breeding and Genetics at Cambridge University, and became best known for his studies of elm. His most famous publication was the seminal Elm, published in 1983, in which he sank many elms formerly treated as species as mere varieties or subspecies of Ulmus minor, notably the English ElmU. procera, which he renamed U. minor var. vulgaris. Richens' all-England collection of specimen elm leaves, along with comparative samples from the Continent, assembled at the Cambridge Department of Applied Biology, is now held at the Cambridge University Herbarium in the Sainsbury Laboratory.
Richens' approach has been much criticized since his death, and some of his taxonomy challenged or discarded. Dr Max Coleman of the Royal Botanic Garden, Edinburgh writes, however : "The advent of DNA fingerprinting has shed considerable light on the question. A number of studies have now shown that the distinctive forms that Melville elevated to species and Richens lumped together as field elm are single clones, all genetically identical, that have been propagated by vegetative means such as cuttings or root suckers. This means that enigmatic British elms such as Plot Elm and English Elm have turned out to be single clones of field elm. Although Richens did not have the evidence to prove it, he got the story right by recognising a series of clones and grouping them together as a variable species."
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. Studies on Ulmus II. The village elms of southern Cambridgeshire. Forestry 31: 132–146.
. Studies on Ulmus III. The village elms of Hertfordshire. Forestry 32: 138–154.
. Cambridgeshire elms. Nature in Cambridgeshire 3: 18–22.
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b. Studies on Ulmus V. The village elms of Bedfordshire. Forestry 34: 185–206.
. Studies on Ulmus VI. Fenland elms. Forestry 38: 225–235.
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. New designations in Ulmus minor Mill. Taxon 26: 583–584.
. Multivariate analysis of the elms of northern France and England: pooled analysis of the elm populations of northern France and England. Silvae Genetica 27: 85–95..
. On fine distinctions in Ulmus L. Taxon 29: 305–312.
