1. Citrus trifoliata Linnaeus, Sp. Pl., ed. 2. 2: 1101. 1763.
Aegle sepiaria Candolle; Citrus trifolia Thunberg; C. trifoliata subf. monstrosa (T. Itô) Hiroe; C. trifoliata var. monstrosa T. Itô; C. triptera Desfontaines; Poncirus trifoliata (Linnaeus) Rafinesque; P. trifoliata var. monstrosa (T. Itô) Swingle; Pseudaegle sepiaria (Candolle) Miquel.
Trees or treelets, 1-5 m tall. Branches green, flat, ridged when young; spines ca. 4 cm, base flat, apex rufous. Foliage spurs unarmed, developed from dormant buds on twigs of previous year, with very short internodes bearing 1-5 leaves. Leaves palmately 3(-5)-foliolate, in juveniles usually simple or 1-foliolate; petiole narrowly winged; leaflet blades 2-5 × 1-3 cm, central one as long or longer than laterals, midvein with short trichomes when young, margin finely crenulate or entire. Flowers solitary or paired, 3.5-8 cm in diam. Calyx lobes 5-7, basally connate. Petals (4 or)5(or 6), white, obovate, 1.5-3 cm, imbricate. Stamens usually 20; filaments of different lengths. Ovary 6-8-loculed, hairy; ovules 4-8, in 2 rows per locule; style short, thick; stigma clavate. Fruit dark yellow, subglobose to pyriform, usually 3-4.5 × 3.5-6 cm, with coarse ring-shaped furrows or sometimes smooth. Seeds 20-50, broadly ovoid, 0.9-1.2 cm; embryo(s) solitary or several; seed coat smooth or with inconspicuous fine ridges. Fl. May-Jun, fr. Oct-Nov.
● Anhui, Chongqing, S Gansu, N Guangdong, N Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, NW Jiangxi, S Shaanxi, Shandong, S Shanxi, Zhejiang.