Zanthoxylum americanum

The Zanthoxylum americanum, sometimes called the American prickly ash, is part of a group of large shrubs and small trees known as pepper trees, known for their fruits and aromatic foliage. This species, americanum, is characterised by excellent cold resistance, low requirements, very spiny branches, and berries with lemony aromas. Rather discreet but well-armed, this American prickly ash is perfect for a defensive hedge. For this reason, it is best to place it far away from a pathway and wear gloves for harvesting!

Native to eastern North America, the Zanthoxylum americanum belongs to the Rutaceae family, like citrus trees. It has highly aromatic foliage that smells like lemon. This species loses its leaves in the winter, tolerates -25°C, and grows in any well-draining soil, even rocky limestone soil. In nature, it is found on cliffs, high rocky plateaus, in forests, in humid ravines, and thickets.

This small, fast-growing tree easily reaches a height of about 4m (13ft) with a similar spread at maturity. Its habit is graceful, naturally spreading, supported by a few main branches. On the branches, each bud is topped with 2 thorns. Over time, the thorns become dull, resembling small bumps. The branches bear deciduous leaves arranged alternately, composed of 5 to 11 (sometimes 13) ovate dark green leaflets, with pockets of essential oil and small spines. When crushed, they release a fresh lemony scent. Flowering occurs in May-June, earlier or later depending on the climate, on one-year-old branches. It consists of small inconspicuous yellowish-green flowers in the axils of the leaves. This shrub has both male and female flowers. After pollination, round fruits, 3 to 4 mm (1in) in diameter, form on the female flowers with their peel turning black when ripe. These fruits are aromatic and have a strong flavour and have an anaesthetic effect (similar to cloves). It is said that Native Americans chewed them to relieve toothaches.

The Zanthoxylum americanum integrates well into an English-style garden or a wild garden. Left to grow freely, it naturally finds its place in an untrimmed hedge, alongside fruiting dogwoods (Cornus mas), sorb trees, viburnums, Amelanchier ovalis, Osage orange, ornamental apple and cherry trees, bee tree. The spiny nature of its young branches makes this beautiful shrub an ideal candidate for a defensive hedge. When grown as a defensive hedge, it can be planted alongside hardy orange, firethorn, jujube tree, hawthorn, Japanese quince, sea buckthorn.