Flora of North America species comparison

Amelanchier laevis is common through much of its range and readily identified by its typically arborescent habit, leaves that are reddish and glabrous by flowering, and relatively long inflorescences, pedicels, and petals. Southeastern United States populations tend to be restricted to high elevations. The relationship to its closest relative, A. arborea, is discussed under the latter.

Amelanchier laevis frequently hybridizes with congeners, including A. arborea, A. bartramiana, A. canadensis, A. humilis, A. interior, A. sanguinea, and A. spicata (M. L. Fernald 1950; L. Cinq-Mars 1971). J. E. Cruise (1964) documented hybrid swarms between A. laevis and both A. arborea and A. canadensis in New Jersey. The hybrid with A. bartramiana can usually be found when these two species grow together (J. E. Weber and C. S. Campbell 1989). The hybrid with A. arborea, A. ×grandiflora Rehder, is used ornamentally.

A. C. Dibble et al. (1998) concluded that Amelanchier laevis is possibly one of the parents of A. "rubra,” an entity that is morphologically distinct. This entity is a tetraploid shrub with stems to 3.5 m and usually colonial, leaves that are reddish and glabrous at flowering, and petals that are often faintly reddish and slightly twisted. Ovary apices are mostly sparsely hairy, but may also be densely hairy or glabrous. Quantitative analysis places A. “rubra” between the cluster of A. laevis plus A. intermedia on the one hand and A. nantucketensis or A. spicata on the other (Dibble et al.). It is possible that this entity could be a hybrid with one of these arborescent species (A. laevis and A. intermedia) plus one of the shrub species (A. nantucketensis and A. spicata). The authors have located populations of A. “rubra” on Mount Desert Island and eastward for about 120 km along the Maine coast. The authors have observed plants that appear to be F1s of this entity and later-generation hybrids with A. bartramiana as one of the parents.

Amelanchier laevis has been documented to be self-compatible and to produce seeds asexually (C. S. Campbell et al. 1985; A. C. Dibble et al. 1998).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Amelanchier bartramiana is the only North American Amelanchier with leaves that are imbricate in bud, usually fewer than four flowers per inflorescence, and conic ovary apices (and hence fruits that are more or less pear-shaped rather than globose as in other members of the genus). Because of these differences, P. Landry (1975) placed A. bartramiana in its own subgenus, and all other members of the genus in another. W. H. Blanchard (1907), W. A. Robinson and C. R. Partanen (1980), and Robinson (1982) also recognized the distinctness of this species. Amelanchier bartramiana grows farther north than any other shadbush in eastern North America, and more than other shadbushes, it occupies relatively undisturbed habitats, such as peatlands and natural breaks in mature forests. Some plants in this species produce seed sexually (C. S. Campbell et al. 1987). Sexual plants of A. bartramiana are self-incompatible diploids; a tetraploid individual has been reported (A. C. Dibble et al. 1998); it had relatively large petals and might have been an autotetraploid.

Amelanchier bartramiana usually flowers with A. laevis, and it frequently hybridizes with other members of the genus. M. L. Fernald (1950) and L. Cinq-Mars (1971) reported hybrids with A. arborea (A. ×quinti-martii Louis-Marie), A. canadensis, A. fernaldii, A. gaspensis, A. humilis, A. intermedia, A. laevis, A. sanguinea, A. spicata, and A. interior. The hybrid with A. laevis can usually be found when these two species grow together (J. E. Weber and C. S. Campbell 1989). The authors have documented a hybrid between A. arborea and A. bartramiana in eastern Pennsylvania (M. B. Burgess et al., unpubl.).

(Discussion copyrighted by Flora of North America; reprinted with permission.)