U. minor “Dehesa de Amaniel”
Universidad Politecnica de Madrid
“Dehesa de Amaniel” is one of the seven Spanish field elm clones initially selected by the Spanish elm breeding programme for crossing with Siberian elm. When these clones’ resistance to elm disease was assessed and found to be surprisingly high, the programme shelved its hybridisation plans and concentrated on developing the seven cultivars in their own right.
As a strain of U. minor, Dehesa de Amaniel is of the same species as the narrow-leaved field elms of Eastern England.
The clone grew from seed collected in 1999 at the Dehesa de la Villa park in North Western Madrid.
Dehesa de Amaniel was tested for disease resistance in 2011 and 2012 by the particularly severe method of inoculation in the lower third of the trunk. It sustained wilting of approximately 3% and 4% in the two years respectively. On any view this is a very good result. However, its full significance becomes apparent only when the scores from those two years for the benchmark-resistant Sapporo Autumn Gold are compared: approximately 32% and 11%.
On the face of it, therefore, Dehesa de Amaniel is very highly resistant indeed. For an U. minor, normally no more than a moderately resistant or positively susceptible species, this performance is quite extraordinary.
The Spanish programme rates Dehesa de Amaniel 3/5 in terms of ornamental value, compared to 4.5/5 for its stable mate Ademuz, and describes its form as “irregular”. Given the one Spanish photograph of the tree (reproduced here), 3/5 seems generous. One must hope that the clone is capable of more attractive form in a less extreme climate.
That said, Dehesa de Amaniel does have some aesthetic virtues. Its leaves are elegantly triple-serrate, rhomboid to orbiculate, ruffled, and somewhat larger than average. The sum of those characteristics is vaguely reminiscent of English Elm. Petioles are short, and the foliage matures to rich dark green with slight gloss. Average annual height increment in Madrid is 90cm, making it the second most vigorous of the 7 Spanish U. minor (just behind Ademuz on 100cm). Corky bark is produced, and the trunk develops character from an early age. The tree leafs fairly early in the season, before Ademuz.
Dehesa de Amaniel is a combination of extremes. On the one hand, a plant with this apparent degree of resistance demands to be taken seriously, and it has some attractive features. On the other hand, if the tree’s form is really no better than the Spanish photograph suggests, there would be no point in planting it. On any view, however, Dehesa de Amaniel is of interest as an element in future hybridisations, where it could contribute genes for resistance.
The tree is undergoing continued assessment in Madrid, and may be released subject to patent in 2016.