Ulmus parviflora Frontier - Elm

Ulmus 'Frontier' is a hybrid elm that is not widely cultivated, but is interesting for its increased resistance to diseases (including Dutch elm disease), its beautiful burgundy-red autumn foliage, and its rather fast growth. It is a deciduous tree of medium size with a wide, airy, slightly irregular crown supported by a vertical central leader. This combination gives this cultivar a graceful appearance. Its foliage is a shiny dark green during the growing season, before changing colour in autumn and falling late in the season. It is a hardy and resistant elm that adapts to a wide range of climates and soils. Suitable for medium to large gardens, it will look good in a grove, in a natural setting. 

Ulmus 'Frontier' is an American horticultural hybrid resulting from the cross-breeding of Ulmus minor and Ulmus parvifolia, from which it inherited its disease resistance. It was introduced by the United States National Arboretum and was commercialised in 1990. The 'Frontier' elm initially has a pyramidal and upright habit, which then widens to become almost oval at maturity. This tree, which grows rapidly in not too dry soil, will reach a height of about 12m (39ft) with a spread of 9m (29ft), depending on growing conditions. The bark that covers the trunk and branches is smooth and grey-green in colour. The deciduous foliage is quite small, entire, and a beautiful shiny dark green. Typically for elms, the lamina is asymmetrical at the base, at the petiole level. The leaves, measuring 6.5 to 11cm (3 to 4in) in length, are oval to ovoid-oblong in shape and have finely toothed edges. In spring, the small elliptical leaves emerge red, then turn a shiny dark green. The tree displays unique autumnal colours for an elm, ranging from scarlet red to purple-red before falling in November. This elm rarely flowers. When it does, it is in September or October, in the form of discreet clusters of greenish-white flowers. 'Frontier' adapts to all types of soil: from dry to wet and from acidic to calcareous, and it tolerates pollution. Additionally, the tree does not produce suckers.

The 'Frontier' Elm will delight gardeners who are looking for a resilient tree with magnificent autumn colours. It can be used in rows along a path, as a standalone tree on a lawn, or in a grove mixed with other species. Its rustic character pairs well with small maples (Acer campestre, A. monspessulanum, A. griseum), purple hazel, or the common hornbeam 'Purpurea'. In autumn, it blends in with the flamboyant colours of deciduous viburnums, winged euonymus, 'Orange Retz' hornbeam, and Persian ironwood, for example.