[(U. glabra var Exoniensis x U. wallichiana) x (U. minor 1 x U. minor 28)] selfed
Dorschkamp Research Institute, Wageningen, NL
Columella is a seedling of Plantyn, open-pollinated, raised by Hans Heybroek in 1967 and released in 1989. It is named for the Roman agronomist who introduced the “English elm” from central Italy into the Iberian peninsula.
Detailed results from inoculation trials are not available, but Columella is generally thought to have excellent resistance to elm disease. In Italy a crossing of Columella with the somewhat less resistant San Zanobi produced FL 589, which with defoliation of 1.44% and dieback of 0% is one of the most resistant elm clones known.
Columella is a stiffly upright and narrow tree intended for street planting. It is thought to reach an ultimate height of about 20 m, and on good soil its growth is fast. Side branching tends to be fastigiate at the top of the tree, becoming more laxly arching further down; the typical form is pillar-like when young, broadening to a flame shape with age. The tree appears to be genuinely monopodial. Columella is said to be notably wind resistant, but ill-suited to withstand drought.
In common with Lutece and Vada, Columella has U. glabra “Exoniensis” in its ancestry, and its leaves are very strongly marked by it. The degree of contortion is such that the foliage appears lumpy. This aspect is not apparent at distances of more than 100 metres. The leaf base tends to curl around the twig, particularly on terminal growth, but the density and rich colour of the canopy are excellent. Leafing is synchronic with field elm, and leaf-fall can be as late as mid-December.
If a street tree is wanted, Columella is vigorous and dependable. Because of its branching, leaf and form, it does not look immediately elm-like. In winter, resemblance to the species is increased. More casually grown, as in the photograph opposite, the lack of definition to the branching is somewhat mitigated and the silhouette is more robust, but this absence of training would not normally be acceptable in a street tree. On rich soil and in an urban setting Columella has a use, but its broader landscape potential seems strictly limited.