Zanthoxylum piperitum

The Zanthoxylum piperitum, sometimes called the Clavalier, is undoubtedly the best-known and most cultivated small Asian tree known as the Sichuan Pepper. Its remarkably aromatic berries are used, especially in Japanese cuisine, under the name of Sichuan Pepper. Its discreet spring flowering is followed by the famous small pink-red berries, whose dried and ground pink husk is used as a spice. The combination of the pink fruits and the foliage taking on shades of golden purple in autumn is superb, and it bears fruit from a young age. It is perfect in a free hedge, and its young, thorny branches are ideal for a defensive hedge. For this reason, it is best to place it far enough from a walkway and wear gloves for harvesting!

Originally from Sichuan province, located in southwestern China, the Zanthoxylum piperitum is widely found from Japan to Vietnam. It is part of the same family as citrus trees, the Rutaceae family, with which it shares a highly aromatic foliage. The Zanthoxylum genus can be hard to tell apart because of the number of leaflets or the shape of the flowers, thorns, or main veins in the leaves. This large bush loses its foliage in winter, occasionally tolerates -18°C (1°F) and develops in well-draining and sufficiently deep soil. Late frosts can, however, harm flowering and burn its young shoots. The Chinese pepper tree is tough and can grow in almost any condition except for dense shade.

Growing rapidly in cool and fertile soil, this small tree reaches an average height of 4m (13ft) with a roughly equal span at maturity. Its habit is elegant, naturally bushy and spreading, supported by flexible branches. The trunk and young stems are adorned with thin, flat thorns that widen significantly at the base over the years while their tips become blunt. They eventually form curious growths that resemble large warts. The branches bear deciduous leaves arranged alternately, 7 to 15 cm (3 to 6in) long, divided into 11 to 21 small ovate and shiny leaflets, toothed along the edges, produce essential oils and small spines. When crushed, they emit a scent that is spicy, woody, lemony, and slightly peppery but mild. They are a beautiful dark green, taking on yellow, orange, and rose-purple tones in autumn before falling. The flowering already appears on plants 3 or 4 years old (from sowing). It occurs in May-June, more or less early depending on the climate, on one-year-old branches. It consists of small clusters or cymes, 3 to 5 cm (1 to 2in) in diameter, composed of small cup-shaped flowers with a yellow-green colour. This shrub has both male and female flowers. After pollination, round fruits form on the female flowers, 3 to 5 mm (1in) in diameter, spherical and verrucose. The fruit is pink-red when ripe, opening to reveal black and shiny seeds. Only the husk is consumed once dried and ground. Note that the Clavalier tolerates pruning very well, even severe pruning. If the plant is self-fertile, fruit production will be greater if you plant 2 or more in the garden.

In the kitchen:

It's important to know that the pink berries from the Sichuan pepper tree are different from the "pink berries" or "pink pepper" sold in the spice section, which come from another tree called Schinus terebinthifolius from South America. 

If you're cooking, you can use the pink "skin" of the Zanthoxylum fruits to add flavour to preserves, rice, salads, and cooked dishes. This spice is essential 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:

To create a charming garden, you can plant a small tree with attractive bark. It's perfect for an English-style or naturalistic garden. You can also plant it alone to showcase its beauty. To do this, prune the lowest branches up to 1m (3ft) from the ground. 

This tree can also be planted in an untrimmed hedge alongside other shrubs like dogwoods, rowans, viburnums, Osage oranges, ornamental apples, cherries, or honey locusts. Its young branches are thorny, making it an excellent choice for a defensive hedge. If you want to use it this way, plant it with Poncirus trifoliata, Rosa moyesii, Pyracantha, hawthorn Crataegus monogyna, Japanese quince Cido, or sea buckthorn.