Zanthoxylum americanum

Zanthoxylum americanum (sometimes spelled Xanthoxylum americanum), the Common prickly-ash, Common pricklyash, Common prickly ash or Northern Prickly-ash (also called Toothache tree, Yellow Wood, and Suterberry), is an aromatic shrub or tree native to central and eastern portions of the United States and Canada. It can grow to 10 metres (33 ft) tall with a diameter at breast height (DBH) of 15 centimetres (6 in). It produces membranous leaflets and axillary flower clusters. The wood is not commercially valuable, but oil extracts from the bark have been used in alternative medicine and have been studied for antifungal and cytotoxic properties.

Taxonomy

Originally described by Scottish botanist Philip Miller in 1768, Zanthoxylum americanum is a member of the wide-ranging genus Zanthoxylum in the Rutaceae family, which includes many species with aromatic foliage. Miller, who spelled the name Xanthoxylum, described the plant in the eighth edition of his Gardeners Dictionary, as "grow[ing] naturally in Pensylvania[sic!] and Maryland".

Description

The plant has membranous leaflets numbering between 5-11 and growing in opposite pairs. It has "axillary flower and fruit clusters". The buds are hairy. Dark green leaves are bitter-aromatic, with crenate margins. The berries begin red and turn deep blue to black, with stalked fruit pods. Flowers are dioecious, with yellow-green petals.

Distribution and conservation status

Rare in the South, it is more common in the northern United States. It is listed as Endangered in Florida, Maryland, and New Hampshire; and as Special Concern in Tennessee. It can be found in Alabama, Arkansas, Connecticut, Washington, DC, Delaware, Florida, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Virginia, Vermont, Wisconsin and West Virginia in the United States, and in Ontario and Quebec in Canada.

Butterflies that use Zanthoxylum americanum for a food source include the Thoas Swallowtail (Papilio thoas), Giant Swallowtail (P. cresphontes), and Spicebush Swallowtail (P. troilus).

Medicinal use

Traditional

An oil extracted from the bark and berries of the prickly-ash (both this species and Zanthoxylum clava-herculis) is used medicinally. The extract may act as a stimulant, and historic medicinal use has included use "for chronic rheumatism, typhoid and skin diseases and impurity of the blood..." as well as for digestive ailments. Grieve states, "The berries are considered even more active than the bark, being carminative and antispasmodic, and are used as an aperient and for dyspepsia and indigestion; a fluid extract of the berries being given, in doses of 10 to 30 drops." The bark has been chewed for toothaches, and a tea from the berries has been used for sore throats and as a diuretic.

Modern studies

There have been some modern studies of the oil's constituents and antifungal properties and cytotoxic effects.