Amelanchier alnifolia
Amelanchier nantucketensis
alder-leaf shadbush, amélanchier à feuilles d'aulne, saskatoon, saskatoon berry, saskatoon serviceberry, service berry, western serviceberry
Nantucket serviceberry, Nantucket shadbush
mostly unfolded;
petiole (3–)6.8–19.1(–28) mm;
blade usually elliptic to oval to suborbiculate, sometimes quadrangular, (14–)24–47(–67) × (7–)17–36(–55) mm, base usually subcordate to truncate, sometimes ± tapering or ± cuneate, each margin with 0–3(–9) teeth on proximal 1/2 and (0–)3–5(–8) teeth in distalmost cm, largest teeth more than 1 mm, apex rounded to truncate or occasionally acute or mucronate, abaxial surface sparsely to densely hairy (or glabrous) by flowering, sparsely to moderately hairy (or glabrous) later, adaxial glabrous or sparsely (moderately) hairy 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–)6–11(–16)-flowered, (8–)14–43(–62) mm.
(4–)6–8(–11)-flowered, (12–)24–36(–53) mm.
(0 or)1 or 2(or 3) subtended by a leaf, proximalmost (2–)3–20(–29) mm.
(0 or)1(or 2) subtended by a leaf, proximalmost (4–)7–14(–38) mm.
sepals erect to recurved after flowering, (1.4–)2.2–4(–4.9) mm;
petals oblanceolate to oval or obovate to elliptic, (5.7–)9.5–14(–18.8) × (2.2–)3.3–5.2(–6.6) mm;
stamens (10–)15–21(–22);
styles (3 or)4 or 5(or 6), (1.3–)2–2.9(–3.9) mm;
ovary apex moderately to densely 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.
black or purple, 8–15 mm diam.
dark purple-blue, 7.5–10 mm diam. 2n = 4x.
Amelanchier alnifolia
Amelanchier nantucketensis
Varieties 3 (3 in the flora).
Amelanchier alnifolia is widespread and polymorphic, and its taxonomic and geographic limits have been viewed differently. L. Cinq-Mars (1971) considered this species to range eastward to the Gaspé Peninsula. Disagreements about the boundary between A. alnifolia and A. humilis are evident in herbarium specimen annotations. The distinctness of the varieties of A. alnifolia has also been questioned. G. N. Jones (1946) treated the three varieties recognized here as distinct species and noted that the leaves of var. alnifolia and var. semiintegrifolia (A. florida) are virtually indistinguishable, and, although petal lengths of the two do not overlap, occasional larger-flowered var. alnifolia and occasional smaller-flowered var. semiintegrifolia occur, so the petal length distinction is not an absolute one. Geographically these two varieties are largely separate, with var. alnifolia occurring in the Great Plains and Rocky Mountains and var. semiintegrifolia on the Pacific slopes of mountains from Alaska to northern California.
Amelanchier alnifolia is thought to hybridize with Sorbus scopulina (x\Amelasorbus jackii Rehder).
(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.)
1. Ovary apices glabrous (or sparsely hairy); shrubs 1–2(–4) m. | var. pumila |
1. Ovary apices moderately to densely hairy (or glabrous); shrubs or trees, 1–12 m | → 2 |
2. Inflorescences (8–)26–43(–62) mm; proximalmost pedicels (5–)8–16(–29) mm. | var. alnifolia |
2. Inflorescences (8–)14–26(–35) mm; proximalmost pedicels (2 or)3–8(–13) mm. | var. semiintegrifolia |
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
KS Wildflowers, 
MN Wildflowers, 
PNW Herbaria, 
SW CO Wildflowers, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
Go Botany
MD Biodiversity
