Zanthoxylum piperitum

Zanthoxylum piperitum (L.) DC. (Rutaceae), Japanese pepper or sanshō, is a deciduous, strongly aromatic shrub or small tree 2-5 m tall, native to Japan, the Korean peninsula and parts of northeastern China, where it grows in mixed deciduous forest, forest margins and rocky slopes. The grey bark of trunk and branches bears characteristic paired flattened spines at the leaf bases. Leaves are alternate, pinnately compound 5-15 cm long, with 9-19 ovate to elliptic, crenate leaflets 1-3 cm long, conspicuously dotted with translucent oil glands and emitting a citrus-pepper aroma when bruised. The species is dioecious: small yellow-green flowers appear in spring in short axillary panicles 2-5 cm long, the males with five stamens and the females with one or two carpels. Fruits are small reddish follicles 5 mm across that split open to expose a single shining black seed and release a pungent aromatic oil from the pericarp. The pericarp, leaves and seeds are widely used as the Japanese pepper spice.