Amelanchier cusickii
Amelanchier bartramiana
Cusick's serviceberry, Cusick's shadbush, saskatoon
amélanchier de Bartram, Bartram's serviceberry, mountain serviceberry, mountain shadbush, mountain shadbush or serviceberry, oblongfruit serviceberry
fully unfolded;
petiole (9–)12.8–19(–28) mm;
blade elliptic to suborbiculate, (22–)33–46(–61) × (13–)25–32(–50) mm, base subcordate to truncate, each margin with (0 or)1–6(–11) teeth on proximal 1/2 and (2–)4 or 5(–7) teeth in distalmost cm, largest teeth 1 mm, apex usually truncate, sometimes mucronate to acute, abaxial surface glabrous or sparsely hairy by flowering, glabrous (or sparsely hairy) later, adaxial glabrous later.
half-unfolded;
petiole (2–)4.5–10.5(–25) mm;
blade narrowly elliptic-oval to oblong to broadly oval, (26–)37–51(–74) × (12–)20–29(–48) mm, base usually cuneate, each margin (2–)8–14(–27) teeth on proximal 1/2 and (2–)7–12(–21) teeth in distalmost cm, largest teeth less than 1 mm, apex acute to rounded, abaxial surface sparsely (moderately) hairy (or glabrous) by flowering, glabrous or sparsely hairy later, adaxial glabrous (or sparsely hairy) later.
(4–)6–8(–10)-flowered, (17–)26–36(–47) mm.
(1 or)2 or 3(or 4)-flowered, (6–)13–25(–38) mm.
(0 or)1 or 2 subtended by a leaf, proximalmost (4–)9–14(–18) mm.
(0 or)1(–3) subtended by a leaf, proximalmost (4–)11–21(–35) mm.
sepals erect to recurved after flowering, (2.6–)3.3–4.3(–5.3) mm;
petals obovate to oblanceolate, (10.8–)13.3–20.1(–23.2) × (2.3–)3.3–6.3(–7.5) mm;
stamens (14–)18–20(–21);
styles (4 or)5, (1.7–)2.6–4(–4.8) mm;
ovary apex glabrous or sparsely hairy (or with a ring of hairs at base of styles).
sepals ascending to recurved after flowering, (1.7–)2.7–3.9(–6) mm;
petals oblong-oval to broadly elliptic, (5.5–)7.1–8.7(–16.9) × (2.6–)3.9–5.3(–7) mm;
stamens (8–)18–21(–25);
styles (3 or)4 or 5, (2.7–)3.8–5.2(–6.1) mm;
ovary apex densely hairy (or glabrous).
bluish black, 10 mm diam. 2n = 4x.
dark purple, pear-shaped, 10–15 mm diam. 2n = 2x, 3x, 4x.
Amelanchier cusickii
Amelanchier bartramiana
Amelanchier cusickii has distinctively long petals. Leaves that are glabrous upon expanding and glabrous or sparsely hairy ovary apices are also useful for identification. The species flowers before A. alnifolia, which suggests that the two are genetically distinct. G. N. Jones (1946) noted that A. alnifolia and A. cusickii frequently grow together and that there is no evidence of hybridization; the authors have observed hybridization between A. alnifolia var. semiintegrifolia and A. cusickii.
(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.)
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