Green Prickly Ash (Zanthoxylum americanum) is a native plant known by common names like Common Pricklyash, Northern Prickly Ash, and Toothache Tree. It belongs to the citrus family (Rutaceae), not true ash trees. This deciduous shrub or small tree is indigenous to central and eastern North America, across the United States and Canada. Its branches are aromatic and thorny.
Identifying Green Prickly Ash
Recognizing Green Prickly Ash requires observing its physical attributes. It typically grows as a multi-stemmed shrub, 8 to 10 feet tall, though it can occasionally develop into a small tree up to 25 feet in height. Its leaves are alternate and pinnately compound, with several smaller leaflets along a central stalk. Each leaf can be up to a foot long and usually has 5 to 11 (sometimes up to 13) dark green, ovate to elliptic leaflets. When crushed, the leaves emit a distinct lemony fragrance.
The stems and branches are armed with sharp, stout prickles, about 1/2 inch long, often flattened and curved. These prickles are usually found in pairs at or below leaf petiole attachment. The bark is generally dark brown.
Small, greenish-yellow flowers appear in axillary clusters in early spring, before leaves fully emerge. These flowers attract bees. Female plants produce clusters of rounded, reddish-brown, berry-like fruits (follicles) that mature in late summer. Each follicle typically contains one to two shiny black seeds.
Where Green Prickly Ash Grows
Green Prickly Ash thrives in various natural settings across North America. It is commonly found in open woodlands, along forest edges, in moist ravines, and within thickets. This adaptable plant also establishes itself in disturbed areas and pastures. While it prefers moist, well-drained soils, it tolerates a range of soil types, including rocky or calcareous soils, and tolerates occasional drought and wet sites.
Its distribution extends from Quebec, west to eastern North Dakota, and south through the eastern and central U.S. to Georgia, Alabama, Oklahoma, and eastern Kansas. It is widespread in states like Illinois, Michigan, Missouri, New York, Ohio, and Pennsylvania. The plant’s ability to form dense thickets and tolerate various conditions allows it to colonize diverse habitats, from bluffs and upland rocky hillsides to roadsides.
Uses of Green Prickly Ash
Green Prickly Ash has been used, particularly in traditional medicine and culinary practices. Historically, Native American tribes used different parts for medicinal properties. The common name “Toothache Tree” originates from chewing the bark or fruits to alleviate toothache pain due to their numbing effect. This numbing quality is shared with Sichuan pepper, another Zanthoxylum genus member.
Beyond toothaches, traditional medicinal uses included decoctions from bark and roots for fever, coughs, rheumatism, and external wounds. Its leaves, bark, and fruits are known for their pleasant lemony fragrance, making them suitable for potpourri. While not true Sichuan pepper, the fruits have been used as a peppery spice in cooking, offering a similar pungent and aromatic quality.
The plant also plays an ecological role, as a food source for giant swallowtail butterfly larvae, sometimes leading to defoliation. Its flowers attract pollinators like bees, and its berries provide food for birds in late summer and winter. While not widely used in landscaping due to its thorny nature and tendency to sucker, its unique appearance and hardiness can make it suitable for barrier plantings.
Important Safety Considerations
While Green Prickly Ash has historical uses, caution is important for its consumption and application. All parts of the plant, including the leaves, bark, and fruits, contain compounds that can have physiological effects. Some individuals may experience side effects or allergic reactions, especially if consumed in large quantities or improperly prepared.
Due to its potent properties, certain populations should avoid use. Pregnant women or individuals on specific medications may experience contraindications. Accurate identification is paramount to prevent confusion with similar-looking but potentially harmful plants. Consult a qualified healthcare professional or botanist before using Green Prickly Ash for medicinal purposes.