Zanthoxylum coreanum

The Zanthoxylum coreanum, sometimes called Pepper tree or Korean Clavalier, is part of a group of small Asian trees known for their aromatic fruits used in cooking. This species, coreanum, less thorny than its cousin simulans, deserves attention for its vigour, hardiness, and large red-orange thorns. Small berries follow discreet spring flowering, and the dried and ground peel is used as a spice. The combination of red fruit and cut foliage turning yellow in September-October is superb. This large bush is ideal as a hedge, and its thorny branches can be used as a defensive hedge. 

Originally from Korea and China, the Zanthoxylum coreanum belongs to the same family as citrus trees, the Rutaceae family, which shares a highly aromatic foliage. In nature, it is often found not far from valleys and coasts, at an altitude between 700 and 1100 m (2297 and 3609ft). This deciduous species loses its foliage in the winter, can withstand temperatures down to -20°C (1°F) and grows in well-drained and sufficiently deep soil. Late frosts can, however, harm its flowering and burn its young shoots. The Korean pepper tree grows well, but it doesn't do well in drought or dense shade.

This small tree, which grows very quickly in cool and fertile soil, measures an average of 4 m (13ft) in height with a similar spread at maturity. Its habit is graceful, naturally spreading, supported by flexible branches. The trunk and branches are adorned with large thorns that widen over the years while their tips become blunt. The branches bear spiny leaves arranged alternately, with a central vein that is not winged, distinguishing it from Z. simulans. Each leaf that produces essential oil comprises 4 to 7 shiny, oblong, elliptical-shaped leaflets with toothed edges. The upper side of the leaflets is deep green, while the underneath is lighter and duller. In autumn, before falling off, the leaflets turn yellow. When crushed, the leaves release a mildly spicy, woody, lemony, and slightly peppery scent. Flowering occurs on plants that are already 3 or 4 years old. It takes place in May-June, depending on the climate, on one-year-old branches. The shrub consists of small clusters or cymes which measure 3 to 5 cm (1 to 2in) in diameter. It is composed of small yellow-green flowers that do not have petals. Both male and female flowers can be found on this shrub. Once pollinated, the female flowers produce round fruits that are spherical and warty, measuring 3 to 5 mm (1in) in diameter. As they ripen, their fleshy peel changes from red to brown, and they open to reveal black and shiny seeds that are highly sought-after by birds. Only the peel is consumed once dried and ground.  

In the kitchen:

The berries of the Korean pepper tree are not the same as the "pink berries" or "pink pepper" sold in the spice aisle. The Brazilian pepper tree, native to South America, produces the latter. The Zanthoxylum's fruit's brown "skin" is used in cooking to enhance preserves, rice, salads, and cooked dishes, particularly in traditional Asian cuisine. Dried and powdered leaves are also used, especially in Japan, as they have a similar aroma to the berries.

In the garden: 

This small tree has a charming quality, making it ideal for an English-style or naturalistic garden. It can be a stunning specimen if grown alone and will impress your visitors. You can prune the lower branches to expose the trunk up to 1 metre (3 feet) from the ground. If left to grow freely, it fits naturally into an untamed hedge alongside dogwoods, rowans, viburnums, osage oranges, ornamental apples and cherry trees, and honey locusts. The spiny nature of its young branches makes it a good choice for a defensive hedge, though it is less of a deterrent than its cousin, the Zanthoxylum simulans.