Fraxinus pennsylvanica 'Summit'

Fraxinus pennsylvanica ‘Summit’ (Green ash ‘Summit’) was found and introduced in 1957 by Summit Nurseries in Stillwater, USA. The tree has an upright and symmetrical crown in its juvenile form which, as it matures, becomes broader and tops out broadly oval to round. The straight trunk penetrates high into the densely branched crown. Fraxinus pennsylvanica ‘Summit’ reaches an ultimate height of ten to sixteen metres and between seven and ten metres wide. 

The green budding, composite foliage of ‘Summit’ is made up of shiny lanceolate leaves. The leaf stays green in the summer and early in the autumn changes to a stunning bright yellow after which it drops from the tree fairly early. Fraxinus pennsylvanica ‘Summit’ blooms in April with inconspicuous yellow-green plumes or panicles and despite being most likely female, the tree bears no seeds. In its juvenile state, the bark is smooth and prone to sunburn but as the tree matures a more grooved bark develops and this tendency declines.

The uniform crown and its very upright main trunk make Fraxinus pennsylvanica ‘Summit’ an excellent choice in avenues, green verges or in streets, provided it is planted in semi-paved areas. The tree is resistant to salt spray and also strong winds and coastal winds, as well as brief flooding and - on fertile soil - periods of drought. The selection ‘Summit’ also anchors firmly thanks to its deep taproot. These characteristics make the tree suitable for planting in urban areas but Fraxinus pennsylvanica ‘Summit’ also stands out in parks and large gardens with its beautiful autumn colour. On ground that does not allow the tree to develop its roots it can force up the paving and consequently a substrate very well suited to improving the habitat of trees is important. It is advisable to prune to shape and thin out to ensure good crown development early on.