A deciduous shrub increasing by sucker growths from the base and forming a thicket of stems 6 to 12 ft high; young shoots and under-surface of leaves downy when young. Leaves broadly oval, obovate, or ovate, toothed nearly to the base; 1 to 21⁄4 in. long. Flowers opening in late April and May on erect woolly-stalked racemes 2 in. long; white, the oblong petals 1⁄3 in. long, broadening towards the end. Fruit blue-black on stalks up to 1⁄2 in. long.
This amelanchier has been known in cultivation for over a century and is probably a hybrid between A. canadensis (oblongifolia) and A. stolonifera, between which it is intermediate in stature. The sepals crowning the fruit provide a distinction; in canadensis they are erect, in stolonifera they are recurved, but in × spicata they spread more or less horizontally.
Many American botanists consider that the Crataegus spicata of Lamarck is not the plant described above but the common dwarf amelanchier of eastern N. America (see under A. stolonifera) and accept the combination A. spicata (Lam.) K. Koch as the valid name for that species. If this view were correct (but it has been disputed), then some other name would have to be found for the plant of European gardens described above.
From the Supplement (Vol. V)
A deciduous shrub increasing by sucker growths from the base and forming a thicket of stems 6 to 12 ft high, even higher (to about 20 ft) on the continent; young shoots and undersurface of the leaves downy when young. Leaves broadly oval, obovate or ovate, toothed nearly to the base, 1 to 2[1/4] in. long. Flowers opening in late April and May on erect woolly-stalked racemes 2 in. long, the oblong petals about [3/8] in. long. Top of ovary hairy. Fruits blue-black on stalks about [1/2] in. long, with only slightly spreading sepals.
This amelanchier has been cultivated in Europe since the late 18th century. It was most probably originally introduced to France, where it was first described, from somewhere in eastern North America, or it may have arisen by hybridisation in Europe. It is very near to A. stolonifera, differing in its much taller growth and non-reflexing sepals. It behaves as a species, and is naturalised in parts of northern Europe and, less commonly, in central Europe, but has not been recorded in Britain, where it has not been cultivated to any extent. It has little ornamental value in flower, and its leaves drop early in the autumn without colouring.
Some American botanists consider A. spicata to be identical with A. stolonifera, and indeed G. N. Jones sinks in it both this species and A. humilis. Other views are that it is a hybrid between A. canadensis and A. stolonifera, or even between A. canadensis and the European A. rotundifolia. It is discussed by Schroeder in his paper of 1972 referred to under A. lamarckii.