I am a landscape designer, and I want to use Amelanchier in my design. Which species are most readily available in the trade? I have seen some which have a single trunk, and others which are multiple. Is the growth habit specific to the species or cultivar?
From what I can tell by searching Plant Information Online, there are quite a few cultivated varieties and species of Amelanchier which are widely available from both retail and wholesale sources.
As far as which species and cultivars are more likely to have single or multiple trunks, I found a few descriptions in Dirr’s Hardy Trees and Shrubs by Michael Dirr (Timber Press, 1997.
- Amelanchier arborea is described as “a small tree or a large multistemmed shrub of rounded outline.”
- Amelanchier canadensis “is hopelessly confused in the landscape trade. In general, it is an upright, suckering, tightly multistemmed shrub with a dome-shaped crown.”
- Amelanchier x grandiflora is “a naturally occurring hybrid between Amelanchier arborea and A. laevis. It exhibits characteristics intermediate between those of the parent species […] The best of the [cultivars] include: ‘Autumn Brilliance,’ with red fall color, ‘Ballerina,’ with brick-red fall color, and ‘Princess Diana,’ with red fall color. ‘Robin Hill’ and ‘Rubescens’ have pink buds that fade upon opening.”
- Amelanchier laevis is “not too different from the other species, especially Amelanchier arborea, in flower, fruit, bark, and growth habit. The principal differences are the purplish to bronze color of the emerging leaves and lack (almost) of hairs on the leaves and flower stalks.”
Here at the Center for Urban Horticulture, we have a grove of Amelanchier x grandiflora, all of which are multi-stemmed. Arthur Lee Jacobson lists several additional species in his North American Landscape Trees (Ten Speed Press, 1996), including the Northwest native Amelanchier alnifolia, which he says is “little planted, especially as a tree.” Its leaves are rounder, with coarser teeth. It flowers later, and its fall color is inferior. Its berries are larger.
You might also explore the Oregon State University Landscape Plants database to see comparative images and descriptions.
If you want to intervene and shape the growth habit of Amelanchier, the American Horticultural Society’s Pruning & Training (edited by Christopher Brickell; DK Publishing, 1996) says that this “upright, multi-stemmed shrub can be allowed to develop naturally with minimal pruning. It may also be trained with a short trunk to form a small, branched-headed tree.” The time to prune would be when dormant in the winter, or after flowering in late spring.