North America Native Plant

Twolobe Spineflower

Botanical name: Chorizanthe biloba

USDA symbol: CHBI2

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Twolobe Spineflower: A Rare California Native Worth Protecting in Your Garden Meet the twolobe spineflower (Chorizanthe biloba), a delicate annual that’s as charming as it is conservation-worthy. This little California native might not win any flashy flower contests, but it’s got something special that makes it a meaningful addition to ...

Rare plant alert!

Region: Conservation status by state

Status: S3: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘

Twolobe Spineflower: A Rare California Native Worth Protecting in Your Garden

Meet the twolobe spineflower (Chorizanthe biloba), a delicate annual that’s as charming as it is conservation-worthy. This little California native might not win any flashy flower contests, but it’s got something special that makes it a meaningful addition to the right garden.

What Makes Twolobe Spineflower Special

The twolobe spineflower is a true California original, found nowhere else in the world except within the Golden State’s borders. As an annual forb, it completes its entire life cycle in one growing season, producing small, inconspicuous flowers that might seem humble at first glance. Don’t let its modest appearance fool you – this plant plays an important role in California’s native ecosystems.

What really sets this spineflower apart is its conservation status. With a Global Conservation Status of S3, it’s considered vulnerable throughout its range. This means there are typically only 21 to 100 known occurrences or between 3,000 and 10,000 individuals in the wild. That makes every garden-grown specimen potentially valuable for conservation efforts.

Where Does It Grow Naturally

Twolobe spineflower calls California home, thriving in the state’s unique Mediterranean climate zones. You’ll find it naturally occurring in USDA hardiness zones 8-10, where it has adapted to the characteristic wet winters and dry summers of California’s coastal and inland regions.

Garden Appeal and Landscape Role

While twolobe spineflower won’t be the star of your flower border, it brings subtle beauty and ecological value to the right setting. Its delicate, herbaceous structure works wonderfully in:

  • Native California plant gardens
  • Xeriscaping and drought-tolerant landscapes
  • Naturalized areas and meadow gardens
  • Ground cover in appropriate native settings

The plant’s low-growing habit makes it perfect for filling in spaces between larger native shrubs and perennials, creating a natural, layered look that mimics California’s wild landscapes.

Benefits for Pollinators and Wildlife

Don’t underestimate this modest annual’s ecological punch. Twolobe spineflower attracts small native bees and other beneficial insects, providing important nectar sources during its blooming period. These tiny pollinators are often overlooked but play crucial roles in maintaining healthy ecosystems.

Growing Conditions and Care

Like many California natives, twolobe spineflower is surprisingly easy to please once you understand its preferences:

  • Sunlight: Full sun exposure
  • Soil: Well-draining sandy or rocky soils (avoid heavy clay)
  • Water: Drought-tolerant once established; mimics natural rainfall patterns
  • Maintenance: Minimal care required

The key to success is replicating its natural habitat conditions. Think well-drained soils and a watering schedule that follows California’s natural dry summer pattern.

Planting and Propagation

As an annual, twolobe spineflower grows from seed each year. In ideal conditions, it may self-seed, creating naturalized patches over time. Plant seeds in fall to align with the species’ natural germination cycle, allowing winter rains to trigger growth.

Important Conservation Considerations

Here’s the critical part: Due to its vulnerable conservation status, only source twolobe spineflower seeds or plants from reputable native plant nurseries that ethically collect from sustainable populations. Never collect seeds or plants from wild populations, as this could further threaten already vulnerable communities.

Look for nurseries that participate in conservation programs or work with botanical gardens and conservation organizations. Some native plant societies also organize seed exchanges with properly sourced materials.

Is Twolobe Spineflower Right for Your Garden

Consider adding twolobe spineflower to your garden if you:

  • Live in California’s Mediterranean climate zones
  • Want to support native plant conservation
  • Appreciate subtle, naturalistic beauty over flashy blooms
  • Are creating a native habitat garden
  • Value plants with important ecological roles

While it might not be the showstopper of your garden, twolobe spineflower offers something more valuable: a chance to participate in conserving California’s unique botanical heritage while creating habitat for native pollinators. Sometimes the most meaningful plants are the quiet ones that work behind the scenes to support the bigger picture.

Remember, every responsibly grown twolobe spineflower in cultivation is a small victory for conservation – and that’s something truly worth celebrating in any garden.

Twolobe Spineflower

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Caryophyllidae

Order

Polygonales

Family

Polygonaceae Juss. - Buckwheat family

Genus

Chorizanthe R. Br. ex Benth. - spineflower

Species

Chorizanthe biloba Goodman - twolobe spineflower

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