Zanthoxylum clava-herculis
Common Name: southern prickly-ash 
Type: Tree
Family: Rutaceae
Native Range: Southeastern United States
Zone: 7 to 9
Height: 15.00 to 30.00 feet
Spread: 10.00 to 25.00 feet
Bloom Time: April to May
Bloom Description: Greenish-yellow to white
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Suggested Use: Hedge
Flower: Showy, Fragrant
Leaf: Fragrant
Attracts: Butterflies
Other: Thorns

Culture

Winter hardy to USDA Zones 7-9 where it is easily grown in moist, well-drained soils in full sun to part shade. Tolerates poor soils. Often is found growing in the wild in sandy coastal plain soils. Freely colonizes by root suckers to form dense thickets. Dioecious (male and female flowers appear on separate trees).

Noteworthy Characteristics

Zanthoxylum clava-herculis, commonly known as hercules-club, southern prickly ash, toothache tree, pepperbark or tingle tongue, is a small, spiny, often thicket-forming, gray-barked, small deciduous tree of the southeastern U.S. It typically grows to 25-30’ (rarely to 50’) tall, but often matures to a much shorter height as a large shrub. It is noted for its spiny trunk and branches plus its leathery compound leaves. It is primarily native to the coastal plains of the Atlantic Ocean and Gulf of Mexico from southern Virginia to mid-Florida west to Texas, often being found in sandy soils on river banks, island bluffs or dunes. Pinnate compound leaves (each to 5-8” long) have 7-9 (19) hairless, crudely toothed and lopsided leaflets which are shiny green above and dull green beneath. Small pale green to greenish yellow to almost white flowers bloom in elongated clusters in April-May. Flowers are followed by red seed pods which appear only on female trees. Leaves, bark and flowers are aromatic when cut or bruised.

Genus name comes from the Greek words xanthos meaning yellow and xylon meaning wood for the color of the heartwood of some species.

Specific epithet comes from the Latin clavatus meaning club-shaped plus the name of the ancient Greek hero Hercules whose favorite weapon was a large gnarled wooden club.

Common name of southern prickly ash is in reference to the resemblance of this tree, particularly the foliage, to an ash tree with prickles. It is not an ash, however, but a member of the citrus family (Rutaceae) and is closely related to the also spiny Poncirus trifoliate (hardy orange).

Native Americans and early settlers reportedly chewed the bark and leaves of this tree as a toothache remedy (oils produce a tingling/numbing sensation in the mouth), hence the additional common names of toothache tree, tingle tongue and pepperbark.

Problems

No serious insect or disease problems. Hercules-club is a food plant for larvae of the giant swallowtail butterfly, and considerable defoliation may occur in some years.

Garden Uses

This tree or shrub has somewhat limited ornamental value. Good for hedgerows, screens, naturalized woodland areas or integrated into native plantings.