Amelanchier spicata

Thicket shadbush, amélanchier en épis

Description
Shrubs. Stems 1–30, 0.3–1.2(–2) m, suckering and in loosely scattered colonies, straggling-ascending; twigs glabrous at flowering. Leaves conduplicate in bud; half-expanded, usually pale green, abaxially densely tomentose by flowering; petioles 8–18 mm; blades abaxially green, oval to orbiculate, 1.5–6.5 x 1–4 cm, thick to coriaceous, bases subcordate or rounded, margins serrate in distal 2/3 or all the way to base with (5–)6–8 teeth per cm, lateral veins mostly 6–9 pairs, anastomosing and becoming indistinct near margins , apices acute to obtuse and often mucronate, surfaces mostly glabrous or with remnants of gray tomentum. Inflorescences (4–)5–7(–10)-flowered, erect, 1.5–4 cm, only proximalmost 1–2 pedicels subtended by leaf. Pedicels sparsely tomentose or glabrous, proximalmost 0.7 –1.6(–2.2) cm. Flowers: hypanthia campanulate, 3–5 mm diam.; sepals recurving after flowering , 2.3–3 mm, adaxially hairy; petals white to ivory, linear-oblong, 6–10 x 2.5–4(–5) mm, not andropetalous; stamens 20; styles 5; ovary summit rounded, densely hairy. Pomes purple-black, glaucous, 7–12 mm diam., sweet. 2n = 34, 51, 68.


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

Habitat
Summits and cliffs of low mountains, open woods, woodland clearings, rocky soils, crevices, shores, fields, roadsides, in peaty, sandy, or gravelly and typically acidic soils; 0–12 00 m

Range
N.B., Nfld. & Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Ala., Conn., Del., Ga., Ill., Iowa, Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Pa., R.I., S.C., Vt., Va., W.Va., Wis.

Discussion
(see Systematics page for references cited)
Amelanchier spicata is strongly suckering and has finely toothed leaves and a densely hairy ovary summit. Amelanchier spicata is similar to A. humilis in habit and vestiture of the ovary summit, but differs in leaf teeth, whether leaf veins clearly enter the teeth, hypanthium shape, and fruit diameter. Amelanchier spicata prefers acidic soils while A. humilis is a calciphile. How A. spicata and A. nantucketensis differ is discussed under A. nantucketensis.

The correct name for Amelanchier spicata has been much debated. K. M. Wiegand (1912) discussed specimens and exsiccati of Crataegus spicata that were made from North American plants grown in European gardens. He said of these specimens: “Those who have seen these specimens and the type specimen of Crataegus spicata, as well as the specimens of our Eastern American stoloniferous fine-toothed Amelanchier agree that they all appear to be one and the same thing. Flowers and leaves in the exsiccati match those of this stoloniferous species as well as one could wish, as do also the flowers and leaves in the original descriptions. The original description of C. spicata, however, gives the height of the plant as from two to three times that of the native species of Amelanchier, which, figured out, would mean 2–5 m.” The native European species is A. ovalis. Because of this difference in stem height, K. M. Wiegand published A. stolonifera. G. N. Jones (1946) analyzed photographs of the type of C. spicata and concluded that this taxon matched his concept of a taxon that included several low, rhizomatous shadbushes (A. erecta, A. gaspensis, A. humilis, A. lucida, A. mucronata, A. stolonifera, and A. austromontana). M. L. Fernald (1946b), supporting Wiegand, emphasized the difference in height and pointed to some differences in number and proximity of leaf veins and orientation of sepals. We have examined a high-quality image of the type of C. spicata, and it resembles closely the rhizomatous fine-toothed Amelanchier that most treatments of eastern North American Amelanchier refer to as A. stolonifera. The stem-height argument is not compelling because “two to three times that of the native species of Amelanchier” specifies a height only by inference.

The andropetalous taxon Amelanchier oblongifolia var. micropetala Robinson was transferred to A. stolonifera as forma micropetala (Robinson) Rehder. The type of this entity, however, has petals that fall within the size range of those of A. nantucketensis, and it is considered a synonym of the latter.

L. Cinq-Mars (1971) considered Amelanchier spicata var. spicata to be a suckering plant to 7 m and to have sepals that are erect or spreading at flowering, and A. spicata var. stolonifera (Wiegand) L. Cinq-Mars to be less than 1 m and to have sepals that are recurved at flowering.

M. L. Fernald (1921) published Amelanchier lucida as a variety of A. stolonifera (without flowering material) based on its lustrous leaves; in 1948 he elevated it to species. G. N. Jones (1946) lumped A. lucida into A. spicata. P. M. Catling ( 2006) analyzed the morphology, including flowers, of A. lucida and concluded that it is distinct from A. spicata because of its shiny leaves and erect orientation of the sepals at flowering. Amelanchier lucida closely resembles A. spicata in overall habit, leaves, inflorescences, and fruits. We have observed somewhat lustrous leaves in A. spicata. We therefore include A. lucida in A. spicata.

M. L. Fernald (1950) and L. Cinq-Mars (1971) reported hybrids between this species and Amelanchier arborea, A. bartramiana, A. intermedia, A. laevis, and A. sanguinea. Plants determined to be apomictic and attributed to this species by C. S. Campbell et al. (1987) were actually A. nantucketensis.