Dai Dai Hua

Citrus aurantium var. amara, the bitter or Seville orange, is a small to medium-sized evergreen tree in the Rutaceae, 4 to 10 meters tall with a dense, rounded crown and stiff, often sharply spiny branches. The bark is grey-brown and the alternate leaves are leathery, broadly ovate to elliptic, 7 to 10 cm long, with a faintly crenulate margin and a characteristically broadly winged petiole. The leaves and other tissues are dotted with translucent oil glands that release a strong citrus aroma when crushed. Flowers are borne singly or in small axillary clusters, white, very fragrant, 2 to 3 cm across, with five thick fleshy petals and numerous yellow stamens; these are the source of orange-flower water and neroli oil. The fruit is a hesperidium 7 to 8 cm in diameter, with a rough, deep orange rind rich in essential oil and a markedly bitter, sour pulp. The dried flower bud and flower constitute the drug Dai Dai Hua.