North America Native Plant

Obtuse Buckthorn

Botanical name: Frangula rubra obtusissima

USDA symbol: FRRUO

Life cycle: perennial

Habit: shrub

Native status: Native to the lower 48 states  

Synonyms: Rhamnus rubra Greene ssp. obtusissima (Greene) C.B. Wolf (RHRUO)   

Obtuse Buckthorn: A Native California Shrub Worth Considering If you’re looking to add native plants to your California or Nevada garden, you might have come across obtuse buckthorn (Frangula rubra obtusissima). This lesser-known native shrub is part of the buckthorn family and offers an interesting option for gardeners seeking to ...

Obtuse Buckthorn: A Native California Shrub Worth Considering

If you’re looking to add native plants to your California or Nevada garden, you might have come across obtuse buckthorn (Frangula rubra obtusissima). This lesser-known native shrub is part of the buckthorn family and offers an interesting option for gardeners seeking to support local ecosystems with indigenous plants.

What Is Obtuse Buckthorn?

Obtuse buckthorn is a perennial, multi-stemmed woody shrub that’s native to the western United States. You might also see it listed under its scientific synonym Rhamnus rubra Greene ssp. obtusissima, as plant classifications sometimes shift over time. This shrub typically stays manageable in size, usually growing to less than 13-16 feet tall, making it suitable for many garden settings.

Where Does It Grow Naturally?

This native beauty calls California and Nevada home, where it has adapted to the unique climate and growing conditions of the region. As a truly native species to the lower 48 states, it has co-evolved with local wildlife and fits naturally into western ecosystems.

Why Consider Obtuse Buckthorn for Your Garden?

Here are some compelling reasons to consider this native shrub:

  • Native plant benefits: Supporting local ecosystems by choosing plants that belong in your region
  • Manageable size: Won’t overwhelm smaller gardens with its moderate height
  • Multi-stemmed growth: Creates natural, informal screening or backdrop plantings
  • Drought adaptation: Likely well-adapted to local rainfall patterns

The Challenge: Limited Information

Here’s where things get interesting (and a bit challenging). Obtuse buckthorn appears to be a subspecies that isn’t widely documented in popular gardening resources. This could mean a few things:

  • It might be quite rare or have a very specific habitat range
  • It could be primarily of interest to botanists rather than home gardeners
  • Information might be limited to scientific publications

Should You Plant It?

While we’d love to give you specific growing tips and detailed care instructions, the limited available information about this particular subspecies makes it tricky to recommend with confidence. If you’re interested in obtuse buckthorn, here’s what we suggest:

  • Contact local experts: Reach out to native plant societies in California or Nevada
  • Check with botanical gardens: They might have experience with this subspecies
  • Consider alternatives: Look into other Frangula or Rhamnus species that are better documented
  • Source responsibly: If you do find this plant, make sure it comes from reputable native plant nurseries

Alternative Native Options

If you’re drawn to the idea of native buckthorns but want something with more available growing information, consider researching other native Rhamnus or Frangula species in your area. Your local native plant society can point you toward well-documented alternatives that will give you the native plant benefits you’re seeking with clearer growing guidelines.

The Bottom Line

Obtuse buckthorn represents an interesting piece of California and Nevada’s native plant puzzle. While its limited documentation makes it challenging for home gardeners to grow with confidence, it highlights the incredible diversity of native plants in our regions. Sometimes the most rewarding gardening adventures come from exploring these lesser-known natives – just make sure you have expert guidance along the way!

Obtuse Buckthorn

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Rhamnales

Family

Rhamnaceae Juss. - Buckthorn family

Genus

Frangula Mill. - buckthorn

Species

Frangula rubra (Greene) V. Grub. - red buckthorn

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