The Elm is one of our commonest trees, yet a great amount of uncertainty appears to prevail in the popular mind in identifying the Common or Small-leaved from our second British species, the variously-named Scotch Elm, Wych Elm, Witch Hazel, or Mountain Elm (Ulmus montana). There is something more than a suspicion that campestris is not strictly indigenous, but it settled in the country so many hundreds of years ago (brought hither, some say, by returning Crusaders) that it would appear ungenerous at this date to question its claims to be called British, especially as it is more widely diffused than montana. The Elms are both tall trees, but campestris usually attains a slightly greater height than montana, though the latter has a much stouter trunk. Their flowers appear before the leaves, and, although they are individually minute and inconspicuous, they are united in bundles, and the colour of the perianth and stamens renders them conspicuous. The perianth is bell-shaped, cleft into five or more lobes, reddish; the purple anthers are equal in number with the divisions of the perianth, to which their filaments are attached. The two styles are awl-shaped, their inner surfaces stigmatic. The flower-cluster is succeeded by a bunch of one-seeded samaras, winged all round. In montana the seed is placed in the centre of the samaras; in campestris it is distinctly above the centre. The leaves of montana are as large again as those of campestris, broader at the base, more inclined to be unequally heart-shaped. There are, however, many varieties of each, which make the identification of the species often very difficult.

The flowers appear in March and April, those of campestris a little earlier than the others. The name is the Latin word for the tree but probably derived from the Hebrew ul, to be strong or vigorous.