Zanthoxylum piperitum

Zanthoxylum piperitum, sometimes called the Clavalier or Chinese pepper tree, is probably the most widespread of these small Asian trees known as Sichuan peppers. Once dried and ground, it is the skins of its incredibly aromatic berries that are used in Chinese and Japanese cuisine, under the name of Sichuan pepper. Often available as a young plant, this small tree can also be grown from seeds. In late autumn, cold stratification should be practiced by placing the seeds at around 4°C (39.2°F) for 3 to 4 months to break dormancy, then sowing at a temperature of 18 to 20°C (64.4 to 68°F) with constant humidity.

Native to the Sichuan province in southwestern China, Zanthoxylum piperitum is widely found from Japan to Vietnam. It belongs to the same family as citrus trees, the Rutaceae family, with which it shares a highly aromatic foliage. The few species that make up the Zanthoxylum genus are sometimes difficult to differentiate, often determined by the number of leaflets that make up the leaves or by morphological characteristics such as the flower, thorns, or main leaf vein. This tall bush loses its foliage in winter and thrives in well-draining and sufficiently deep soil. Late frosts can, however, damage its flowering and burn its young shoots. Only dense shade discourages this intrepid Chinese pepper tree.

Growing rapidly in moist and fertile soil, this small tree reaches an average height of 4 metres (13 feet) with a similar spread at maturity. Its habit is elegant, naturally bushy and spreading, supported by flexible branches. The trunk and young branches are adorned with slender flat thorns that widen at the base over the years, while their tips become blunt. They eventually form curious growths resembling large warts. The branches bear deciduous leaves arranged alternately, measuring 7 to 15cm (3 to 6in) in length, divided into 11 to 21 small ovate and glossy leaflets, toothed at the edges, with essential oil glands and small prickles. When crushed, they release a scent that is spicy, woody, lemony, and slightly peppery, but mild. They are a beautiful dark green colour, turning yellow, orange, or pinkish-purple in autumn before falling. Flowering already occurs on plants aged 3 or 4 years (since sowing). It takes place in May-June, earlier or later depending on the climate, on one-year-old branches. It consists of small clusters or cymes, 3 to 5cm (1 to 2in) in diameter, composed of small cup-shaped flowers in a yellow-green colour. This shrub has both male and female flowers. After pollination, round fruits, 3 to 5mm (0.25in) in diameter, spherical and verrucate, form on the female flowers. Their fleshy envelope turns pink-red when ripe, opening to reveal black and shiny seeds. Only the envelope is consumed once dried and ground. Note that the Chinese pepper tree tolerates pruning very well, even severe pruning.

On the table:

The pink berries of this Sichuan pepper tree should not be confused with "pink berries" or "pink pepper" sold in the spice aisle: these are produced by another small tree called Schinus terebinthifolius, the Brazilian pepper tree, native to South America. In cooking, we use the pink "skin" of the fruits of our Zanthoxylum to enhance preserves, rice, salads, and cooked dishes. This spice is essential in traditional Asian cuisine. Dried leaves reduced to powder are also used, especially in Japan: their aroma is very similar to that of the berries.

In the garden:

This small tree with fascinating bark is charming in an English or naturalistic garden. If planted in isolation, it can become a beautiful specimen over time, which will earn you surprised remarks from your visitors: you can perfectly prune the lower branches to expose its trunk, up to 1 metre (3 feet) from the ground. Left unpruned, it naturally fits into an untrimmed hedge, alongside dogwoods, rowans, viburnums, Osage orange, ornamental apple and cherry trees, or bee tree, for example. The spiny nature of its young branches makes this handsome shrub an ideal candidate for a defensive hedge. In this use, for example, combine it with Poncirus trifoliata, Rosa moyesii, Pyracantha, Crataegus monogyna, Cido, and sea buckthorn.

Organic or "AB" seeds come from plants grown without pesticides (insecticides, herbicides). These seeds also do not undergo any post-harvest treatment. They bear the AB label and are certified by Ecocert, an independent organization.