Ulmus minor var. plotii (Mill.) Richens, known as Plot's Elm, or Lock Elm, is found only 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 mistook the tree as Goodyer's Elm Ulmus stricta (now U. minor subsp. angustifolia) var. goodyeri Melville. The trees Goodyer described are confined to the Hampshire coast east of Lymington, and very dissimilar in structure.
'Plot's Elm' was a tree with a most distinctive habit. Before the advent of Dutch elm disease, this slender tree grew to a height of 30 m and was chiefly characterized by a crooked trunk curving near the summit, supporting a few short ascending branches to form a narrow, cocked crown; 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. The samarae rarely ripen, but when mature are narrowly obovate, < 13 mm in length, with a triangular open notch.
Pests and diseasesEdit
Ulmus minor var. plotii is very susceptible to Dutch elm disease.