Zanthoxylum americanum (Syn. Xanthoxyum Americanum) is commonly known as the Toothache tree, Prickly ash, or Prickly-ash.
The plant belongs to the Rutaceae family and is thus closely related to citrus and Rue.
This tree ranges between 15 to 20 feet (4.5 to 6 m) in height and has a spread of 10 to 15 feet (3 to 4.5 m) wide.
Zanthoxylum americanum is a native of Eastern North America. It grows well in US zones 3 to 7, and is thus tolerant of temperatures down to about minus 40 degrees.
zanthoxylum americanum photograph by Manuel.
Its leaf structure is a compound pinnate format with dark green leaves.
The tree blooms with beautiful flowers in the spring, followed by leaf growth. These flowers are a greenish-yellow colour and are fragrant.
Ornamental fruits appear on female trees once flowering has completed, reaching maturity in the summer. They have a berry like appearance and are a red-brown colour.
It gained one of its common names, the Toothache tree, because of its medicinal properties.
Native Americans would chew the bark or fruits for toothache relief. Other medicinal properties of this tree are associated with fevers, coughs, rheumatism, and external wounds. Bark infusions were also traditionally used to enhance the sense of smell in hunting dogs.
An attractive (one of the few) feature of Prickly Ash is that birds and butterflies (Swallowtail) seek out this tree for protection and as a food source.
The twigs and branches emit a strong lemon peel odor when snapped.
New plants can be grown from seeds, root cuttings or from their suckers. To collect seeds, collect the seed capsules, and let dry. The capsules will open and release their seeds upon drying out.
Seeds will require cold weather to germinate, so sow the fresh seeds in the autumn (or stratify them in the fridge).
Zanthoxylum americanum requires full sun for best results but is moderately shade tolerant.
This tree can thrive in droughts as well as moist ravines and thickets.
Prickly ash can tolerate poor soils so long as they are well-drained.
This is not a plant recommended to be grown inside as the needles can reach up to half an inch long.
It is not recommended to grow for ornamental purposes, though it does fairly well when used for hedge rows and screens. As they have sharp thorns they can also be used as a barrier planting.