Amelanchier interior

Wiegand’s shadbush, amélanchier de l’intérieur

Description
Shrubs or small trees. Stems 1–10, 1–10 m. often straggling or arching; twigs glabrous at flowering. Leaves conduplicate in bud; unfolded but not fully grown, reddish to green, abaxially sparsely pubescent or +/- glabrous by flowering; petioles 10–30 mm; blades abaxially green, broadly ovate to elliptic, 3–7 x 2–5 cm, thin or firm, bases rounded to subcordate, margins serrate nearly to or to base with 4–6(–9 ) teeth per cm, lateral veins 7–12 pairs, anastomosing and becoming indistinct near margins , apices short acuminate to apiculate, surfaces glabrous. Inflorescences 4–12-flowered, drooping or nodding, 3–7.5 cm, proximalmost 1–2 pedicels subtended by leaf. Pedicels glabrous or nearly so, proximalmost 1.2–4(–4.5) cm. Flowers: hypanthia campanulate, 3–6 mm diam.; sepals recurving after flowering , 2–5 mm, adaxially hairy ; petals white, obovate, 6–15 x 4–5 mm, not andropetalous; stamens 20; styles 5; ovary summit rounded, densely hairy (glabrate). Pomes purple-black, globose, 6–8 mm diam., sweet. 2n = 68.


Flowering/Fruiting
Flowering May–Jun; fruiting Jul–Aug.

Habitat
Dry woods, bluffs above rivers, rocky areas and slopes, banks of streams, fields, thickets, and sandy areas; less often in wetlands; 0–300 m

Range
N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Ill., Iowa, Mich., Minn., Ohio, S.Dak., Wis.

Discussion
(see Systematics page for references cited)
The capacity to grow into a small tree, sparsely hairy young leaves that are often reddish, and the densely hairy ovary summit are distinctive for Amelanchier interior. Amelanchier interior and A. wiegandii were both named by E. L. Nielsen (1939), who differentiated them in a key 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) described these differences as “quite intangible” , and he included A. wiegandii in A. interior. We follow Jones, but retain the common name of Wiegand’s shadbush because of Wiegand’s early insights about the taxonomy of the genus. M. L. Fernald (1950) considered A. wiegandii as “suggesting a small leaved no. 18 [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 (1985) 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 the latter two species. Moreover, 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 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 lowest pedicels, sepals, and petals. The leaves of A. wiegandii were described as “bronze in color at flowering time” (E. L. Nielsen 1939 ), but G. N. Jones had the leaves of A. interior as “green … when young” . We assume that A. interior as we interpret it is polymorphic for the color of young leaves.