Elms: Northern & Southern Wych Elm

Elm is perhaps the most significant group of plants in Britain where taxonomic consensus is weak. As botanists we generally work to the taxa published in Stace’s New Flora of the British Isles (edn. 4); here 7 elms are listed. Sell & Murrell1, by contrast, list sixty-two! Happily (or not, depending on your viewpoint), most of these are localised in coastal regions of the South-west, or in East Anglia, where it is tempting to think they may have originated in the vast wet woodlands that would once have characterised the area.

Two of the Sell & Murrell taxa are relevant to us in vc36, however. Whereas Stace lists a single Wych Elm, Ulmus glabra Huds., which has been incorporated into most county-based recording cards, Sell & Murrell split off trees from the southern part of the range as Ulmus scabra Mill. Confusingly, they give the common name ‘Wych Elm’ to this taxon, in distinction to Ulmus glabra Huds. which they term ‘Northern Wych Elm’. The Welsh Marches span the junction of these two taxa and it will probably be less confusing for us if we adopt the terms Southern Wych Elm Ulmus scabra Mill. and Northern Wych Elm Ulmus glabra Huds.

Northern Wych Elm Ulmus glabra Huds. Leaves catch the eye by being conspicuously longer than typical for Herefordshire (as per Sell & Murrell’s key, more than twice as long as wide – both these 2.2x). Note also the absence of horns on this leaf (again, as per the key, this taxon is not supposed to have them).
Southern Wych Elm Ulmus scabra Mill. More typical (!) Herefordshire Wych Elm with proportionately shorter leaves (here 1.75x longer than wide); size is not diagnostic, but proportions are. Note also some material has ‘horns’, as permitted in the key.

We can leave the taxonomists to the nomenclatural debate, but we shouldn’t let their lack of agreement hold us back on understanding the plants that grow in our region.

At the time of writing I have only found Southern Wych Elm in Herefordshire, but last week at a BSBI conference in Shropshire, I came across what looked like Northern Wych Elm at Nesscliffe Country Park, north-west of Shrewsbury. These are the leaves shown on the left. The site is c 80km north of our county boundary. I would like to ask all botanists, but especially those working in the North-west of Herefordshire, to look out for the Northern taxon. Where does the frontier between the two lie? There’s a county first at stake here for anyone willing to up their game!

1 Sell, P. & Murrell, G. (2018) Flora of Great Britain & Ireland Vol 1. CUP.

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