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Amelanchier
See list of 10 species in this genusDespite its small size, Amelanchier is a difficult genus. Frequent hybridization creates local, novel morphologies that can be very confusing, especially on herbarium sheets where the plants are removed from the context of sympatric species. Several species that exist in multiple races based on ploidy level sometimes differ subtly from one another. There also exist undescribed morphologies in New England, particularly in the eastern half of ME. Use caution when assessing leaf teeth/vein characters, as the character states used in the key are for normal growth. Stump sprouts possess misleading leaves. Given that determinations are significantly easier to perform on flowering material, every effort should be made to collect during this brief time in the spring. References: Wiegand (1912), Jones (1946).
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1a. Flowers borne in fascicles of 1–4; leaves imbricate in bud, with the outer ones enfolding the inner ones in bud, at maturity with petioles 2–10 mm long, cuneate at the base; bark often brown; ovary summit conical and pubescent
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1b. Flowers borne in racemes of 4–10 (–15); leaves conduplicate and positioned beside one another in bud, at maturity with petioles (8–) 10–30 mm long, rounded to cordate at the base; bark often gray; ovary summit rounded, pubescent or glabrous
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2a. Petals 3–6 (–7) mm long, sometimes pollen-bearing [Fig. 827]; plants colonial, with many close stems up to 2 (–3) m tall
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2b. Petals (6–) 7–22 mm long, not bearing pollen; plants colonial or not, 0.3–13 m tall
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3a. Summit of the ovary pubescent (note: character state visible in flower and fruit); sepals reflexed from near the middle in fruit
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4a. Lateral veins of leaf blade visible but not prominent, curved forward, forking 3 or more times, anastomosing and evanescent near the margin, not extending into the teeth [Fig. 829]; margin of leaf blade usually serrulate with 6–10 teeth per cm, the teeth more than twice as many as primary lateral veins (caution: leaves on stump sprouts can show fewer, larger teeth); fruit 7–12 mm in diameter
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4b. Lateral veins of leaf blade prominent, nearly straight, forking 1 or more times, extending into the teeth or not; margin of leaf blade coarsely serrate-dentate with 0–5 teeth per cm, sometimes entire near the base (or nearly throughout), the teeth less than twice as many as primary lateral veins; fruit 5–8 mm in diameter (up to 10 mm in diameter in A. gaspensis, but that species with leaves sparsely pubescent during flowering)
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5a. Flowering racemes compact, 20–40 (–50) mm long, the rachis and pedicels densely pubescent; lowest pedicel 9–13 (–15) mm long in flower; expanding leaf blades densely tomentose abaxially, retaining the tomentum long after flowering
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5b. Flowering racemes somewhat open, 40–80 mm long, the rachis and pedicels sparsely pubescent; lowest pedicel (7–) 10–30 mm long in flower; expanding leaf blades soon losing much of the abaxial tomentum and becoming glabrescent post flowering
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6a. Low, colonial plants up to 1 m tall; petals 6–9 mm long; leaf blades with 6–13 pairs of primary veins that mostly anastomose near the margin; hypanthium scutelliform, 3–4 mm wide
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6b. Taller shrubs with solitary or clumped stems 1–3 m tall; petals (10–) 11–15 (–20) mm long; leaf blades with 12–15 pairs of primary veins that mostly enter the teeth [Fig. 828]; hypanthium open and shallow, (3.5–) 4–6 (–8) mm wide
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3b. Summit of the ovary glabrous; sepals ascending to recurved in fruit
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7a. Petals 7–12 mm long; racemes straight, erect or ascending, the axis 2.5–6 cm long; sepals ascending to spreading (infrequently recurving) in fruit; stems several to many, close together, forming clumps; mature leaf blades rounded to subcordate at base
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8a. Leaf blades sparsely pubescent and often tinged with purple at anthesis, at maturity truncate to subcordate at the base and acute to short-acuminate at the apex, with 5–7 teeth per cm; petals 9–12 mm long; flowering racemes sparsely pubescent on the rachis and pedicels; lower pedicels 20–35 mm long in fruit; sepals ascending to somewhat recurving in fruit
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8b. Leaf blades densely pubescent and green at anthesis (the blade color obscured by the hairs), at maturity rounded at the base and rounded or mucronate at the apex, with 6–11 teeth per cm; petals 7–10 mm long; flowering racemes densely pubescent on the rachis and pedicels; lower pedicels 5–10 mm long in fruit; sepals erect to loosely ascending in fruit
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7b. Petals 12–22 mm long; racemes lax or arching, the axis 4–12 cm long; sepals recurved in fruit; stems solitary or few together; mature leaf blades cordate at the base
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9a. Leaf blades at anthesis 50–75% expanded, nearly glabrous, strongly tinged with red-purple or purple, essentially glabrous at maturity; lower pedicels 20–50 mm long in fruit; pomes fleshy and sweet
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9b. Leaf blades at anthesis less than 50% expanded, densely tomentose on the abaxial surface, green, retaining some pubescence in maturity especially along the midvein and in the axils of the primary lateral veins; lower pedicels 10–25 mm long in fruit; pomes drier and bland tasting
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Each photo represents one species in this genus.