Amelanchier arborea
Amelanchier canadensis
Allegheny serviceberry, common serviceberry, downy servicberry, downy serviceberry, downy shadbush
amélanchier du Canada, Canada serviceberry, Canadian serviceberry, eastern shadbush
less than half-unfolded;
petiole (5.5–)12–20.6(–29.2) mm;
blade ovate to obovate, (30–)47–68(–93) × (16–)26–40(–56) cm, base cordate to rounded, each margin with (0–)11–21(–30) teeth on proximal 1/2 and (3–)5–9(–13) teeth in distalmost cm, largest teeth less than 1 mm, apex acute to acuminate, abaxial surface densely (moderately) hairy by flowering, glabrous or sparsely to moderately hairy later, adaxial glabrous or sparsely (moderately) hairy later.
less than half-unfolded;
petiole (5–)10–15(–25) mm;
blade elliptic or oval to oblong or obovate, (24–)34–48(–67) × (12–)18–27(–42) mm, base subcordate, rounded, or cuneate, each margin with (0–)6–15(–29) teeth on proximal 1/2 and (0–)6–12(–17) teeth in distalmost cm, largest teeth less than 1 mm, apex subacute or obtuse to rounded and mucronate, abaxial surface densely hairy by flowering, glabrous or sparsely to moderately hairy later, adaxial glabrous or sparsely (moderately) hairy later.
(3–)6–12(–15)-flowered, (19–)30–55(–79) mm.
(3–)7–10(–15)-flowered, (6–)15–37(–74) mm.
0 or 1 subtended by a leaf, proximalmost (5–)10–20(–32) mm.
0 or 1(or 2) subtended by a leaf, proximalmost (1–)5–14(–17) mm.
sepals soon reflexed after flowering, (1.6–)2.3–3.7(–5.3) mm;
petals linear to oblong, (8–)10–15(–19) × (2–)3.1–5(–6.8) mm;
stamens (16–)20(–21);
styles (3–)5(or 6), (2.1–)3.2–4.2(–5.5) mm;
ovary apex glabrous or sparsely (densely) hairy.
sepals erect, ascending, or spreading after flowering, (0.3–)1.8–3.1(–4.6) mm;
petals linear, elliptic, or oblong, (4–)6–10.2(–15) × (1.8–)2.6–4(–5.3) mm;
stamens (15–)19–21(–28);
styles (3–)5(or 6), (1.5–)3.4–4.7(–5.8) mm;
ovary apex glabrous (or moderately hairy).
maroon-purple, 6–10 mm diam. 2n = 2x, 4x.
purplish black or maroon-purple, 6–10 mm diam.
Amelanchier arborea
Amelanchier canadensis
Amelanchier arborea is distinctive for its arborescent habit, generally precocious flowering, leaf margins each with (3–)5–9(–13) teeth on distal cm, densely hairy abaxial surface of leaf blades, and strongly reflexed sepals at flowering. Leaves typically have subcordate to strongly cordate bases, acuminate apices, and margins sometimes finely double serrate.
The name Amelanchier canadensis was applied by many botanists to A. arborea and A. laevis until M. L. Fernald (1941) clarified the issue; this usage appears in some older manuals. McKay transferred A. laevis to subspecific status under A. arborea, and the two species are generally considered to be closely related. Allozyme data show that, with one exception, populations of each are more closely related to a nearby population of the other than they are to conspecific populations (R. D. Overath and J. L. Hamrick 1998). At flowering, A. arborea and A. laevis can be distinguished by leaf color, which is typically reddish green or reddish brown in A. laevis and green to greenish white in A. arborea. In addition, the leaves of A. laevis are at least half-expanded and unfolding as well as glabrous (or sparsely hairy) by flowering, and its sepals are spreading to reflexed.
Amelanchier arborea exhibits considerable variation; infraspecific taxa have been named. Variety alabamensis differs in its densely hairy ovary apices. Variation in ovary summit indument in A. arborea does not appear to be associated with any other taxonomically informative variation; individuals with varying amounts of ovary indument occur sporadically in populations; this does not appear ecologically significant. The authors conclude that this variety does not warrant taxonomic recognition; they have observed groups of populations that differ in the number of flowers per inflorescence, color of the expanding leaves, size of the teeth, and other features.
Amelanchier arborea usually flowers a week or more before sympatric congeners. The species has been reported (M. L. Fernald 1950) to hybridize with A. bartramiana, A. canadensis, A. humilis, and A. laevis. The authors have collected putative hybrids with A. amabilis in New York and have observed putative hybrids between A. arborea and other eastern North American species of Amelanchier. Hybrid swarms in New Jersey between this species and A. laevis but not A. canadensis have been reported (J. E. Cruise 1964).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
The type specimen of Amelanchier canadensis, from Virginia or Canada, includes a single stem with five leaves and the remnants of an infructescence with three fruits. Much of the difficulty in determining the identities of specimens and species distributions owes to the limited diagnostic value of the type. The authors include A. obovalis as a variety of A. canadensis because of ecologic and morphologic similarities. W. W. Ashe (1903) described A. obovalis as a shrub of swamps and loose soils, 9–15 dm or a tree to 4 m with inflorescences 3–5 cm and proximalmost pedicels 3–9 mm at flowering and 20–30 mm in fruit. K. M. Wiegand (1912) described A. canadensis (as A. oblongifolia) as a shrub with slender, erect stems in dense fastigiate colonies with inflorescences 25–60 mm, the proximalmost pedicels 8–18 mm and scarcely longer in fruit. Wiegand was uncertain about placement of specimens of A. obovalis from the southeastern United States and stated that they appeared to be this species. The circumscription by Wiegand of A. oblongifolia and the circumscription by Ashe of A. obovalis overlap considerably. The two species co-occur in similar habitats, have overlapping phenologies, and individual populations may contain specimens with intermediate morphologic characters, especially at early successional sites. Experimental crosses between plants representing the morphologic and ecologic extremes result in formation of mature fruit and seed (C. T. Frye, unpubl.). Plants growing among rocky outcrops in the Potomac River Gorge in Maryland and Virginia suggest A. spicata in growth form and habitat but differ in having glabrous ovary apices and the finely toothed leaves of A. canadensis. These plants are also unusual in that most individuals in the population rarely produce fruits suggesting the presence of locally dominant self-incompatibility allele(s).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Petals (4–)7–10.2(–15) mm; inflorescences (12–)21–37(–74) mm; proximalmost pedicels (6–)8–14(–17) mm; shrubs 0.5–8 m; stems in open to dense colonies. | var. canadensis |
1. Petals (5–)6–8(–10.4) mm; inflorescences (6–)15–27(–45) mm; proximalmost pedicels (1–)5–10(–15) mm; shrubs 0.2–2 m; stems in dense colonies, often evidently stoloniferous. | var. obovalis |
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