Citrus hystrix Dc.

Trees 3-6 m tall. Branchlets with spines. Leaves dark red when young; petiole winged, apex rounded to truncate; leaf blade ovate, 5-8 × 2.5-4.5 cm, 1-2.5 cm longer (rarely same length) and 0.5-1 cm wider than winged petiole, tertiary veins conspicuous, margin apically conspicuously and sparsely crenate, apex narrowly obtuse. Inflorescences with (1 or)3-5 flowers; peduncle 1-5 mm. Flower buds globose. Calyx lobes 4 or 5, broadly triangular, ca. 4 × 6 mm. Petals white but pinkish red outside, 7-10 mm. Stamens ca. 30; filaments distinct. Style short, thick. Fruit lemon yellow, ellipsoid to subglobose, 5-7 × 3-5 cm, slightly coarse or smooth, oil dots numerous and prominent, apex rounded; pericarp thick; sarcocarp in 11-13 segments, very acidic and slightly bitter. Seeds numerous 1.5-1.8 × 1-1.2 cm, ridged; embryo solitary; cotyledons milky white. Fl. Mar-May, fr. Nov-Dec.

A tropical plant. It mainly occurs in lowland areas in the tropics. It suits hardiness zones 10-12. In Yunnan.

The leaves and fruit are used to make drinks or to flavour food. They are added to soups and curries. The leaves are pounded into a jelly and mixed with hot chili pastes. The fruit are eaten crystallised. The juice of the fruit is used for flavouring. The lemon scented fruit are eaten with fish.

Plants can be grown from seed or by grafting. It often now grows wild in coastal areas. It grows slowly.