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Rhamnus
See list of 4 species in this genus-
1a. Flowers with 5 sepals, 0 petals, and 5 stamens; leaves alternate; branches unarmed; plants 0.15–1 m tall
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1b. Flowers with 4 sepals, petals, and stamens [Fig. 824]; leaves alternate, subopposite, or opposite (often displaying all arrangements on a given plant); plants often armed with a spine-like process near the apex of some branchlets or in the forks of some branches; plants up to 10 m tall
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2a. Petioles 5–15 mm long, (0.03–) 0.10–0.16 (–0.23) times as long as the blade; leaf blades with 5 or 6 (–8) pairs of primary lateral veins, abaxially pubescent with gold-yellow hairs on the veins and/or in the leaf axils (at least when young), turning yellow or gold-yellow abaxially when dry
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2b. Petioles 10–40 mm long, (0.08–) 0.25–0.50 (–0.75) times as long as the blade; leaf blades with 3–5 (–6) pairs of primary lateral veins; usually some branchlets and branches on a plant with a spine-like process; leaf blades glabrous abaxially or with ± white hairs on the veins and/or in the vein axils, remaining green to pale green abaxially when dry
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3a. Leaf blades (1.9–) 3–6.6 cm long, 3 or 4 pairs of lateral veins, elliptic to ovate or broad-ovate; drupe with 3 or 4 pyrenes
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3b. Leaf blades (4–) 6–13 cm long, with 4 or 5 (–6) pairs of lateral veins, oblong to elliptic or elliptic-obovate; drupe with 2 pyrenes
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Each photo represents one species in this genus.