Scientific Name: Sonchus palmensis
Common Name: La Palma Sow Thistle
Plant type: Perennial shrub
Environment: Full sun in well-drained soil
Bloom: Large head of small yellow flowers
Uses: Specimen plant
Mediterranean Garden – 28E, 28F
Sonchus palmensis, or La Palma Sow Thistle, is a medium sized shrub of the Asteraceae family. The shrub is endemic, meaning only native to, La Palma, an island in the Canary Island archipelago in the Macaronesian region off of the western coast of Africa.
As a member of the Asteraceae family that is closely related to dandelions (Taraxicum ssp.) one might expect S. palmensis to be a small, herbaceous plant. It is, instead, a relatively large shrub, growing from 4 to 6 ft, with leaves up to 3 ft long! The species also has large bright yellow flower heads that bloom in the spring.
Sonchus palmensis only grows on the island of La Palma, where it is considered to be of “Least Concern” in terms of its conservation status, despite having a limited native range. The species is relatively common there and the population is considered stable.
While there are close to 100 species of Sonchus in Africa, Asia, Australia, and Europe, there are only 24 species in the Canary Islands, and only 5 on La Palma. The Sonchus species of the Canary Islands, along with a handful of other genera in the family, show significant differences in their morphology, anatomy, and ecology, but have been found to have all have developed from a single colonization event in the late Miocene or early Pliocene eras.
Sonchus palmensis is particularly well suited to grow here in San Francisco as its native range has a quite similar climate. Though most of the rain on La Palma occurs during the winter, S. palmensis occurs at elevations between 650 and 3280 ft, in areas that experience cool foggy days in the summer, just as we see here in the Bay Area.
Text and Photos by Victoria Stewart