Ulmus minor subsp. plotii
|Ulmus minor subsp. plotii|
|Plot's Elm, Westonbirt, before 1913
(height 29m, girth 2.1m) 
|Subspecies:||U. minor subsp. plotii|
|Ulmus minor var. plotii
Ulmus minor subsp. plotii (Mill.) Richens, known as Plot's Elm, or Lock Elm, is only found growing naturally in England, where it is encountered mainly in the East Midlands, notably around the River Witham in Lincolnshire and in the Trent Valley around Newark on Trent. It has been described as Britain's rarest native elm, and it is recorded by The Wildlife Trust as a nationally scarce species.
As with other members of the Field Elm group, the taxonomy of Plot's Elm is a matter of contention, several authorities recognizing it as a species in its own right. Indeed, it is as U. plotii that the specimens held by the Royal Botanic Gardens at Kew and Wakehurst Place are listed. Richens, however, contended that it is simply one of the more distinctive clones of the polymorphous Ulmus minor, conjecturing that its incidence in the English Midlands may have been linked to its use as a distinctive marker along Drovers' roads.
Henry miscalled the tree Goodyer's Elm Ulmus stricta (now U. minor subsp. angustifolia) var. goodyeri Melville. The trees Goodyer discovered were near the coast at Pennington, Hampshire, some 200 miles away and very dissimilar in structure.
Before the advent of Dutch elm disease, this slender monopodial tree grew to a height of 30 m and was chiefly characterized by its cocked crown comprising a few short ascending branches; Richens likened its appearance to an ostrich feather.
The obovate to elliptic acuminate leaves are small, rarely > 4 cm in length, with comparatively few marginal teeth, usually < 70; the upper surfaces dull, with a scattering of minute tubercles and hairs.
Pests and diseases
Ulmus minor subsp. plotii is very susceptible to Dutch elm disease.
An uncommon tree even before Dutch elm disease, U. minor subsp. plotii has also been affected by the destruction of hedgerows and by urban development within its limited range. Like other forms of the Field Elm, however, it suckers freely and is thus not considered critically endangered. Conservation measures are now in place to preserve known stands and to encourage propagation. Owing to its susceptibility to Dutch elm disease, it is no longer planted as an ornamental. It is the subject of a study at the Royal Botanic Garden Edinburgh by Dr Max Coleman titled 'The application of RAPDs to the critical taxonomy of the English endemic elm Ulmus plotii (sic) Druce'.
There are no known cultivars of this taxon, nor is it known to be in commerce in Europe.
The tree was first recognized as a distinct form by the Oxford botanist George Claridge Druce in 1908-11, who found examples at Banbury and Fineshade Abbey, and published descriptions with photographs. Druce named the tree for Dr Robert Plot, a 17th-century English naturalist. The synonym 'Lock Elm' is an allusion to the difficulty in working its timber. Bancroft referred to Plot's Elm as the East Anglian Elm, adding that it was often referred to as Wych Elm in the region; however, she was almost certainly alluding to the Smooth-leaved Elm.
Plot's Elm hybridizes in the wild both with wych elm, to form U. × hollandica 'Elegantissima', and with U. minor subsp. minor, to form Ulmus × viminalis. Melville noted that within the limits of the tree's distribution, hybrids are more common than Plot's Elm itself.
Elms of the Ulmus × viminalis group have been cultivated since at least 1677  and have given rise to a hybrid cultivar of that name and to the cultivars 'Aurea', 'Marginata', 'Pulverulenta'. The 19th-century cultivar 'Myrtifolia' was considered by Melville to be a probable U. minor × Ulmus minor subsp. plotii hybrid. The 20th-century dwarf elm cultivar 'Jacqueline Hillier' is thought to belong to the 'Elegantissima' group.
A mature Plot's Elm, with leaves that match those in Stella Ross-Craig's diagram, and with the characteristic inclination in the crown of its monopodial trunk (height 30m, girth 2.5m), survives (2013) on the Alvanley Terrace (Whitehouse Loan) side of Bruntsfield Links, Edinburgh. Since this specimen will have been selected by the plantsmen who turned The Meadows and Bruntsfield Links into an elm collection, and since it has grown to maturity without apparent pruning or storm-damage, it constitutes a rare textbook example of the type.
- North America
- Bartlett tree nurseries. Acc. nos. 7771, 00–108, as U. plotii, provenances not disclosed.
- Brighton & Hove City Council, UK. NCCPG Elm Collection . No details available.
- Cambridge Botanic Garden , University of Cambridge, UK. As U. coritana var. angustifolia, no accession details available.
- Romney Gardens, Cumbria, UK. UK champion 28 m high, 87 cm d.b.h. (1996).
- Wakehurst Place Garden, Wakehurst Place, UK, as U. plotii. Acc. no. 1912-59402, donated by Augustine Henry, acc. nos. 1975–6181, 1975–6195, 1977–6692, all collected by Melville.
- Royal Botanic Gardens Kew, UK, as U. plotii, acc. no. 1969-16753, (planted 1958), donated by Melville.
- Elwes, H. J., & Henry, A., The Trees of Great Britain & Ireland (Private publication, Edinburgh, 1913), Vol. VII, p.1902
- Melville, Ronald, The Journal of Botany, London, Vol.78, Aug. 1940
- Plot’s Elm (Ulmus Plotii). Wildlifebcnp.org. Retrieved on 2011-05-24.
- Coleman, M., Hollingsworth, M. L. and Hollingsworth, P. M. (2000). "Application of RAPDs to the critical taxonomy of the English endemic elm Ulmus plotii Druce". Botanical Journal of the Linnean Society 133 (3): 241–262. doi:10.1111/j.1095-8339.2000.tb01545.x.
- Armstrong, J. V. & Sell, P. D. (1996). "A revision of the British elms (Ulmus L., Ulmaceae): the historical background". Botanical Journal of the Linnean Society 120: 39–50. doi:10.1111/j.1095-8339.1996.tb00478.x.
- Stace, C. A. (1997). New Flora of the British Isles, 2nd edition. Cambridge University Press.
- Melville, R. (1978). "On the discrimination of species in hybrid swarms with special reference to Ulmus and the nomenclature of U. minor (Mill.) and U. carpinifolia (Gled.)". Taxon 27 (4): 345–351. doi:10.2307/1220370. JSTOR 1220370.
- Richens, R. H., Elm, Cambridge 1983, p.54
- Max Coleman, ed.: Wych Elm (Royal Botanic Garden Edinburgh publication, 2009; ISBN 978-1-906129-21-7); p. 22
- Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp. 1848–1929. Private publication.
- White, J. & More, D. (2002). Trees of Britain & Northern Europe. Cassell's, London.
- Chatters, C. (2009) Flowers of the Forest – Plants and people of the New Forest National Park. Wildguides, Old Basing, England. ISBN 978-1-903657-19-5
- Richens, R. H. (1968). The correct designation of the European field elms. Feddes Repertorium 79: 1–2.
- Photograph of young U. minor var. plotii in R. H. Richens, Elm (Cambridge 1983), p. 4
- Photograph of Plot's Elm leaves, elmer.rbge.org.uk
- Wilkinson, Gerald, Epitaph for the Elm, London 1978, pp.72–74
- Gard. Chron. 1.408, figs. 165, 166 (1911)
- Melville, Ronald, Journal of Botany (London, Aug. 1940)
- Wilkinson, Gerald, Epitaph for the Elm (London, 1978)
- Gurney, R. (1958). Trees of Britain. Faber & Faber, London.
- Bancroft, H. (1934). Notes on the Status and Nomenclature of the British Elms. Gardeners' Chronicle XCVI.
- Richens, R. H., Elm, Cambridge 1983
- Plot, Nat. Hist. Oxfordshire, 158, pl.10 fig.1 (1677)
- Bean, W. J. (1988) Trees and shrubs hardy in Great Britain, 8th edition, Murray, London, p.659
- Green, P. S. (1964). Registration of cultivar names in Ulmus. Arnoldia, Vol. 24. Arnold Arboretum, Harvard University. 
- Bean, W. J. (1988) Trees and shrubs hardy in Great Britain, 8th edition, Murray, London, p.653
- Richens, R. H., Elm (Cambridge, 1983), Ch.7
- Plot's Elm (centre), Bruntsfield Links, Edinburgh; henniker.org.uk
- Plot's Elm, Bruntsfield Links, from Links Hotel (photo 50 of 81); tripadvisor.co.uk 
- Johnson, Owen (ed.) (2003). Champion Trees of Britain & Ireland. Whittet Press, ISBN 978-1-873580-61-5.