North America Native Plant

Island Barberry

Botanical name: Mahonia pinnata insularis

USDA symbol: MAPII

Life cycle: perennial

Habit: vine

Native status: Native to the lower 48 states  

Synonyms: Berberis pinnata Lag. ssp. insularis Munz (BEPII)   

Island Barberry: A Rare California Native Worth Protecting If you’re passionate about native plants and conservation, you’ve probably never heard of island barberry (Mahonia pinnata insularis). And honestly, that’s not surprising – this incredibly rare shrub is one of California’s most endangered native plants, found only on select California islands. ...

Rare plant alert!

Region: United States

Status: S5T1: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is critically Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 5 or fewer occurrences or very few remaining individuals (<1,000) ⚘ Secure: At very low or no risk of extinction in the jurisdiction due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats. ⚘ Endangered: In danger of extinction throughout all or a significant portion of its range. ⚘

Region: United States

Island Barberry: A Rare California Native Worth Protecting

If you’re passionate about native plants and conservation, you’ve probably never heard of island barberry (Mahonia pinnata insularis). And honestly, that’s not surprising – this incredibly rare shrub is one of California’s most endangered native plants, found only on select California islands.

What Makes Island Barberry Special?

Island barberry is a perennial shrub that belongs to the mahonia family, known for their distinctive compound leaves and bright yellow flower clusters. As a multi-stemmed woody plant, it typically stays under 13-16 feet tall, making it a manageable size for most landscapes – if you could actually find one to plant, that is.

This native California species has quite the scientific pedigree, previously known by the synonym Berberis pinnata Lag. ssp. insularis Munz. But don’t let the fancy names fool you – this is one tough little plant that has adapted to life on California’s rugged islands.

Where Does Island Barberry Call Home?

Island barberry is native to California, specifically found only on certain California islands. Its extremely limited geographic distribution is part of what makes this plant so special – and so vulnerable.

The Reality Check: This Plant is Endangered

Here’s where things get serious. Island barberry has a Global Conservation Status of S5T1 and is listed as Endangered in the United States. This means we’re talking about a plant that’s hanging on by a thread in the wild. The small population and limited habitat make every individual plant incredibly valuable for the species’ survival.

Should You Grow Island Barberry?

The short answer? Only if you can source it responsibly and legally. Given its endangered status, island barberry isn’t something you’ll find at your local nursery. If you’re serious about growing this rare beauty, you’ll need to:

  • Work with specialized native plant nurseries or conservation organizations
  • Ensure any plant material is legally and ethically sourced
  • Consider participating in conservation efforts rather than just backyard gardening
  • Understand that you’d be taking on the responsibility of caring for a piece of California’s natural heritage

Alternative Native Choices

While you probably can’t grow true island barberry, you can support California’s native plant communities by choosing other mahonia species or related native shrubs that aren’t endangered. Look for more common California natives that provide similar aesthetic appeal and ecological benefits without the conservation concerns.

Why This Plant Matters

Even if you never see an island barberry in person, knowing about plants like this helps us appreciate the incredible diversity of California’s native flora. Each endangered species represents thousands of years of evolution and adaptation to specific environments. When we lose plants like island barberry, we lose irreplaceable pieces of our natural world.

Supporting conservation efforts, choosing native plants for our gardens, and spreading awareness about endangered species like island barberry are all ways we can contribute to preserving California’s botanical heritage for future generations.

The Bottom Line

Island barberry might not be destined for your backyard, but it serves as a powerful reminder of why native plant conservation matters. Whether you’re planning a native garden or just curious about California’s flora, remember that some of our most precious plants are the ones we can’t easily grow – and that makes them all the more worth protecting.

Island Barberry

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Magnoliidae

Order

Ranunculales

Family

Berberidaceae Juss. - Barberry family

Genus

Mahonia Nutt. - barberry

Species

Mahonia pinnata (Lag.) Fedde - wavyleaf barberry

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA