Amelanchier cusickii
Amelanchier interior
Cusick's serviceberry, Cusick's shadbush, saskatoon
amélanchier de l'intérieur, inland serviceberry, Wiegand's shadbush
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.
not fully unfolded;
petiole 10–30 mm;
blade broadly ovate to elliptic, 30–70 × 20–50 mm, base rounded to subcordate, each margin with 3–15 teeth on proximal 1/2 and (2–)4 or 5(–7) teeth in distalmost cm, largest teeth less than 1 mm, apex short acuminate to apiculate, abaxial surface glabrous or sparsely hairy by flowering, surfaces glabrous later.
(4–)6–8(–10)-flowered, (17–)26–36(–47) mm.
4–12-flowered, 30–75 mm.
(0 or)1 or 2 subtended by a leaf, proximalmost (4–)9–14(–18) mm.
1 or 2 subtended by a leaf, proximalmost 10–45 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 recurved after flowering, 2–5 mm;
petals obovate, 6–15 × 4–5 mm;
stamens 20;
styles 5, 3–5 mm;
ovary apex densely (moderately) hairy (or glabrous).
bluish black, 10 mm diam. 2n = 4x.
purple-black, 6–8 mm diam. 2n = 4x.
Amelanchier cusickii
Amelanchier interior
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 interior is distinguished by its capacity to grow into a tree to ten meters and by having sparsely hairy young leaves that are often reddish and densely hairy ovary apices. E. L. Nielsen (1939) differentiated A. interior and A. wiegandii on the basis of leaves being carinate in A. wiegandii as opposed to flat in A. interior, and leaf sinuses rounded versus acute. G. N. Jones (1946) considered those differences to be slight, and he included A. wiegandii in A. interior. The authors follow Jones, but retain the common name Wiegand’s shadbush to commemorate Wiegand’s early insights about the taxonomy of Amelanchier. M. L. Fernald (1950) considered A. wiegandii as suggesting a small-leaved A. laevis but with shorter buds, fewer teeth, fewer veins, and summit of ovary heavily tomentose. P. Landry (1975) thought A. wiegandii to be the hybrid of A. arborea and A. sanguinea, and E. G. Voss (1972–1996, vol. 2) reasoned that A. interior is a hybrid swarm involving A. laevis (or sometimes A. arborea) and plants of the A. spicata and/or A. sanguinea complex. A hybrid origin of A. interior from A. laevis and A. sanguinea is reasonable given that stem height, the number of leaf teeth, and petal length are more or less intermediate between those two species. DNA sequences from ITS region indicate that A. interior (A. wiegandii) is a possible later-generation hybrid involving a member of the western North American ITS clade (which also includes A. humilis and A. sanguinea of eastern North America) and some eastern North American taxon (C. S. Campbell et al. 1997). Multiple hybrid origins, possibly from different species, may explain the variability of A. interior. Amelanchier interior has unusually large ranges of lengths for proximal pedicels, sepals, and petals. The leaves of A. wiegandii were described by Nielsen as bronze at flowering; Jones described the leaves of A. interior as green when young. The authors assume that A. interior as they interpret it is polymorphic for the color of young leaves.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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