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Cusick's serviceberry, Cusick's shadbush, saskatoon

amélanchier intermédiaire, intermediate serviceberry, intermediate shadbush

Habit Shrubs, 2–8 m. Stems 1–50, solitary or in colonies. Shrubs or trees, 2–7 m. Stems 1–50, fastigiate, solitary or in colonies.
Leaves

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 (14–)16–21.8(–24) mm;

blade elliptic to slightly obovate, (39–)46–65(–77) × (25–)26–38(–45) mm, base subcordate or rounded, each margin with (5–)13–19(–20) teeth on proximal 1/2 and (5–)13–19(–20) teeth in distalmost cm, largest teeth less than 1 mm, apex acute to short-acuminate, abaxial surface sparsely hairy by flowering, surfaces glabrous later.

Inflorescences

(4–)6–8(–10)-flowered, (17–)26–36(–47) mm.

(6 or)7–10-flowered, 35–59(–77) mm.

Pedicels

(0 or)1 or 2 subtended by a leaf, proximalmost (4–)9–14(–18) mm.

0 or 1 subtended by a leaf, proximalmost (13–)14–25(–33) mm.

Flowers

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, (2–)3.3–4.5(–5.2) mm;

petals oblong, (10–)12.7–17.7(–18.5) × (3–)3.9–5.3(–5.7) mm;

stamens (18–)20(–21);

styles (4 or)5, (3.3–)3.8–4.8(–5) mm;

ovary apex glabrous (or sparsely hairy).

Pomes

bluish black, 10 mm diam. 2n = 4x.

dark purple, 7–12 mm diam. 2n = 4x.

Amelanchier cusickii

Amelanchier intermedia

Phenology Flowering Mar–Jul; fruiting May–Aug. Flowering May–Jun; fruiting Jun–Aug.
Habitat Basaltic ledges, cliffs, and bluffs along streams, stony soil, streambeds, stream banks, copses, mountainsides, roadsides Swamps, bogs, thickets, shores
Elevation 600–2300 m (2000–7500 ft) 0–1000 m (0–3300 ft)
Distribution
from FNA
ID; MT; OR; WA; BC
[BONAP county map]
from FNA
CT; MD; ME; MI; MN; NC; NH; NJ; NY; PA; SC; VA; VT; NB; NF; NS; ON; PE; QC
[BONAP county map]
Discussion

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 intermedia is morphologically closest to A. laevis. In a study of morphologic variation involving A. canadensis, A. intermedia, A. laevis, and other species of Amelanchier, A. C. Dibble et al. (1998) found that the only two species that overlap are A. intermedia and A. laevis. P. Landry (1975) considered A. intermedia to be the hybrid of A. arborea (including A. laevis) and A. canadensis, and the authors have data that suggest A. intermedia is a hybrid of A. canadensis and A. laevis.

Amelanchier intermedia hybridizes with A. bartramiana, A. humilis, and A. spicata (L. Cinq-Mars 1971).

A. C. Dibble et al. (1998) reported that two individuals of Amelanchier intermedia, both tetraploids, were apomictic.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 9, p. 652. FNA vol. 9, p. 660.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Amelanchier Rosaceae > subfam. Amygdaloideae > tribe Maleae > Amelanchier
Sibling taxa
A. alnifolia, A. amabilis, A. arborea, A. bartramiana, A. canadensis, A. fernaldii, A. gaspensis, A. humilis, A. interior, A. intermedia, A. laevis, A. nantucketensis, A. nitens, A. pallida, A. sanguinea, A. spicata, A. utahensis
A. alnifolia, A. amabilis, A. arborea, A. bartramiana, A. canadensis, A. cusickii, A. fernaldii, A. gaspensis, A. humilis, A. interior, A. laevis, A. nantucketensis, A. nitens, A. pallida, A. sanguinea, A. spicata, A. utahensis
Synonyms A. alnifolia var. cusickii, A. basalticola
Name authority Fernald: Erythea 7: 121. (1899) Spach: Hist. Nat. Vég. 2: 85. (1834)
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