Acanthus is a genus of flowering plants in the family Acanthaceae, best known for two things: its bold, sculptural foliage in gardens and its iconic role as the leaf motif carved into ancient Greek and Roman architecture. About 30 species exist, native to tropical and warm temperate regions across the Mediterranean, Africa, and Asia. Whether you encountered the word on a building, in an art history class, or at a nursery, the same plant is behind all of it.
The Plant Itself
Acanthus plants form large, dramatic clumps of deeply lobed leaves that can spread 4 to 6 feet wide. In late spring or summer, tall flower spikes shoot up from the center of the clump, sometimes reaching 6 feet in height. The flowers are hooded and tubular, typically white or purple with spiny bracts beneath them. Even when not in bloom, the glossy, architectural foliage is the main attraction.
The genus is hardy across USDA zones 6 through 10, which covers a wide swath of the United States and similar climates worldwide. Acanthus tolerates clay, loam, sand, and even shallow rocky soil, but it does not like wet feet. Most species prefer partial shade and well-drained ground. Once established, the plant spreads by underground rhizomes, and it can be difficult to remove. Any small piece of root left in the soil will regrow.
Common Species and How They Differ
The two species you’ll encounter most often in gardens and garden centers are Acanthus mollis and Acanthus spinosus. Their names tell you the key difference. “Mollis” means soft: the leaves are glossy and rubbery with shallow lobes and no spines along the edges. “Spinosus” has narrower, more deeply cut leaves with sharp, numerous spine-tipped lobes. Handling A. spinosus without gloves is noticeably unpleasant.
A third species, Acanthus hungaricus, sits somewhere between the two. Its leaves are deeply dissected with broad gaps between the lobes, but the spine tips are relatively dull. The flower spikes tend to be smaller than those of the other species. For most gardeners choosing between them, the decision comes down to leaf texture and how much space you’re willing to give up, since all three spread aggressively once happy.
Less commonly grown but ecologically important is Acanthus ilicifolius, a mangrove species found in coastal wetlands across South and Southeast Asia. It looks quite different from its Mediterranean cousins, with holly-like spiny leaves adapted to brackish water.
The Corinthian Capital Legend
The acanthus leaf is one of the most recognizable motifs in Western architecture, and its origin story dates back over 2,000 years. The Roman architectural writer Vitruvius, writing around 25 BCE, told the tale of how the motif came to be. A young girl in Corinth had died, and her nursemaid placed a basket of the girl’s favorite belongings near her grave, setting a flat tile on top to keep the contents safe. Acanthus plants grew up around the basket, their broad leaves curling gracefully outward where they met the tile’s edges.
A sculptor named Callimachus passed by, saw the form, and used it as inspiration for a new style of column capital. That became the Corinthian order, the most ornate of the three classical Greek column styles. The acanthus leaf motif appeared in Greek art as early as 500 BCE and has been used continuously ever since, from Roman temples to Renaissance churches to neoclassical government buildings.
Symbolism Across Cultures
Because of its connection to the Vitruvius story, acanthus has long symbolized rebirth, immortality, and resurrection. The plant’s real-world behavior reinforces the metaphor: it is remarkably hard to kill, regrowing vigorously from even small root fragments left in the ground. John Milton referenced acanthus in Paradise Lost (1667), placing it on either side of the entrance to Adam’s bower in Eden. In decorative arts, acanthus scrollwork became shorthand for elegance and endurance, appearing on everything from furniture to textiles to cemetery monuments.
Traditional and Medicinal Uses
Several acanthus species have a long history in traditional medicine. The rhizomes of Acanthus mollis were used historically to treat conditions involving inflammation. Modern chemical analysis of the rhizome found that roughly 70% of its detectable compounds are plant-based sterols, naturally occurring molecules that reduce cholesterol absorption and appear to have anti-inflammatory effects.
Acanthus ilicifolius has been used in both Ayurvedic and traditional Chinese medicine for centuries. Laboratory research has identified a range of active compounds in its leaves, stems, and roots, including phenols, flavonoids, and other molecules with strong antioxidant properties. Leaf extracts showed free-radical scavenging activity approaching that of vitamin C in controlled experiments. The plant has also demonstrated anti-inflammatory, liver-protective, and antimicrobial effects in animal studies, though these findings haven’t translated into mainstream clinical use.
Invasive Potential
Acanthus is not listed as a noxious weed in the United States or on the federal invasive species list. However, it does appear on the Global Invasive Species Database and is classified as invasive in Australia. In mild climates like coastal California, Oregon, and parts of the Pacific Northwest, Acanthus mollis can escape gardens and colonize disturbed ground, roadsides, and woodland edges. Its spreading rhizomes and ability to regenerate from root fragments make it difficult to eradicate once it establishes outside a garden bed.
If you’re planting acanthus in a mild-winter climate, consider containing it with a root barrier or growing it in a spot bounded by hardscape. In colder zones where winter freezes kill the roots back, aggressive spreading is far less of a concern.