Amelanchier interior
Amelanchier nantucketensis
amélanchier de l'intérieur, inland serviceberry, Wiegand's shadbush
Nantucket serviceberry, Nantucket shadbush
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.
less than half-unfolded;
petiole (6–)9–15(–22) mm;
blade elliptic to oblanceolate or oblong-elliptic, (11–)29–41(–55) × (13–)19–29(–42) mm, base rounded to cuneate, each margin with 0–4(–10) teeth on proximal 1/2 and (0–)3–8(–12) teeth in distalmost cm, largest teeth less than 1 mm, apex subacute to rounded and mucronate, abaxial surface densely (moderately) hairy by flowering, surfaces sparsely hairy (or glabrous) later.
4–12-flowered, 30–75 mm.
(4–)6–8(–11)-flowered, (12–)24–36(–53) mm.
1 or 2 subtended by a leaf, proximalmost 10–45 mm.
(0 or)1(or 2) subtended by a leaf, proximalmost (4–)7–14(–38) mm.
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).
sepals irregularly spreading or recurved after flowering, (1.3–)2–3(–3.9) mm;
petals spatulate to oblong, (2.2–)3–4.5(–6.8) × (0.6–)1–2(–3) mm, sometimes bearing 1 or 2 tiny pollen sacs near margins on adaxial surfaces;
stamens (12–)18–20;
styles (4 or)5, (1.7–)2.6–3.7(–4.3) mm;
ovary apex glabrous or sparsely to densely hairy.
purple-black, 6–8 mm diam. 2n = 4x.
dark purple-blue, 7.5–10 mm diam. 2n = 4x.
Amelanchier interior
Amelanchier nantucketensis
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.)
In the absence of flowering material, identification of Amelanchier nantucketensis is tentative; it is easily confused with A. spicata. K. M. Wiegand (1912) thought that A. nantucketensis originated as a hybrid between A. spicata (which he called A. stolonifera) and A. canadensis (as A. oblongifolia).
Amelanchier nantucketensis can reach 2.5 m but is usually much shorter, with spindly, straight, pale gray stems. Some petals of A. nantucketensis bear 1 or 2 tiny pollen sacs near margins on adaxial surfaces. Petal-borne pollen, which is highly unusual within the plant kingdom, is viable in A. nantucketensis and associated with a unique pollinator guild of native bees (A. C. Dibble et al. 1997). Conservation challenges for this apomictic tetraploid were discussed by Dibble and C. S. Campbell (1995).
Amelanchier nantucketensis has been documented to be self-compatible and able to produce seed asexually (C. S. Campbell et al. 1987).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
IL Wildflowers
MI Flora
MN Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
Go Botany
MD Biodiversity
