15b. Amelanchier canadensis (Linnaeus) Medikus var. obovalis (Michaux) Britton, Sterns & Poggenburg, Prelim. Cat. 17. 1888.
Mespilus canadensis Linnaeus var. obovalis Michaux, Fl. Bor.-Amer. 1: 291. 1803; Amelanchier canadensis (Linnaeus) Medikus subsp. obovalis (Michaux) P. Landry
Shrubs, 0.2–2 m. Stems 1–100, forming dense colonies and often evidently stoloniferous. Leaves: blade elliptic or oval to oblong or obovate, (24–)34–40(–62) × (12–)18–27(–38) mm, base subcordate to cuneate, apex acute or obtuse and mucronate, surfaces glabrous (or sparsely hairy). Inflorescences (5–)7–9(–11)-flowered, usually compact, (6–)15–27(–45) mm. Pedicels: (0 or)1 subtended by a leaf, proximalmost (1–)5–10(–15) mm. Flowers: sepals ascending or spreading after flowering, (0.8–)1.8–2.7(–4) mm; petals elliptic, (5–)6–8(–10.4) × (1.9–)2.6–3.5(–4.3) mm; stamens (15–)19–21(–28); styles (3 or)4 or 5(or 6). Pomes purplish black, 6–8 mm diam. 2n = 2x, 3x.
Flowering Mar–May; fruiting May–Jun. Pine savannas, sandhills, roadsides, dry openings in woods, sandy soil; 0–200 m; Del., Ga., Md., N.J., N.C., Pa., S.C., Va.
C. T. Frye (2006) found morphologic evidence of introgression between var. canadensis and var. obovalis; the introgression may have been facilitated by land clearing and other anthropogenic disturbances. Variety obovalis represents a geographic trend towards smaller petal and inflorescence dimensions in the southern range; there is much overlap range-wide. Additionally, characters such as plant height and extent of lateral spread that have been used in major couplets of keys are variable and may largely depend on site disturbance history, for example, mowing, burning. Variety obovalis is self-incompatible and apparently sexual (C. T. Frye, unpubl.) and diploid throughout its range (M. B. Burgess et al., unpubl.). The triploid count (2n = 51) is represented by a single specimen determined by W. A. Robinson and C. R. Partenen (1980).