1. Amygdalus communis Linnaeus, Sp. Pl. 1: 473. 1753.
扁桃 bian tao
Amygdalus amara Duhamel; A. communis var. amara (Duhamel) Candolle; A. communis var. dulcis (Miller) Candolle; A. communis var. fragilis (Borkhausen) Seringe; A. dulcis Miller; A. fragilis Borkhausen; A. sativa Miller; Prunus amygdalus (Linnaeus) Batsch; P. amygdalus var. amara (Duhamel) Focke; P. amygdalus var. dulcis (Miller) Koehne; P. amygdalus var. fragilis (Borkhausen) Focke; P. amygdalus var. sativa (Miller) Focke; P. communis (Linnaeus) Arcangeli (1882), not Hudson (1762); P. communis var. dulcis (Miller) Borkhausen; P. communis var. fragilis (Borkhausen) Focke; P. communis var. sativa (Miller) Focke; P. dulcis (Miller) D. A. Webb; P. dulcis var. amara (Duhamel) H. L. Moore.
Trees or shrubs, (2–)3–6(–8) m tall. Branches erect or horizontally spreading, unarmed, with many short branchlets, glabrous; previous year’s branchlets brownish, grayish brown to grayish black with age. Winter buds brownish, ovoid, 3–5 mm, glabrous. Leaves variable, those on previous year’s branches usually alternate, those on short branches approximate and often fascicled; petiole 1–2(–3) cm, glabrous, with 2 to 4 nectaries at apex or at base of leaf blade; leaf blade lanceolate to elliptic-lanceolate, 3–6(–9) × 1–2.5 cm, slightly pilose when young, glabrescent, base broadly cuneate to rounded, margin shallowly densely serrate, apex acute to shortly acuminate. Flowers solitary, opening before leaves. Pedicel 3–4 mm, 4–10 mm in fruit, glabrous. Hypanthium cylindrical, (5–)6–8 × 3–5 mm, outside glabrous. Sepals broadly oblong to broadly lanceolate, 5–6 mm, outside glabrous, margin pubescent, apex obtuse. Petals white or pinkish, oblong to obovate-oblong, 1.2–2 × 0.7–1.1 cm, base tapering to a narrow claw, apex obtuse to emarginate. Stamens unequal in length. Ovary densely tomentose. Style longer than stamens. Drupe obliquely ovoid to oblong-ovoid, compressed, 3–4.3 × 2–3 cm, densely pubescent, base mostly subtruncate, apex pointed to somewhat obtuse; mesocarp thin, splitting at maturity; endocarp yellowish white to brown, ovoid, broadly ellipsoid, or shortly oblong, asymmetric on both sides, 2.5–3(–4) cm, hard to fragile, ventral suture curved and ± acutely keeled, dorsal suture generally straight, surface smooth and pitted with or without shallow furrows, base obliquely truncate to orbicular-truncate. Seed sweet or bitter. Fl. Mar–Apr, fr. Jul–Aug.
Cultivated in Gansu, Shaanxi, Shandong, and Xinjiang [probably native to SW Asia].
Cultivated varieties of almonds have been named for whether the seeds are sweet or bitter and whether the endocarp is hard or fragile.