North America Native Plant

Serpentine Monkeyflower

Botanical name: Mimulus brachiatus

USDA symbol: MIBR

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Serpentine Monkeyflower: A Rare California Native Worth Protecting Meet the serpentine monkeyflower (Mimulus brachiatus), a tiny treasure of California’s unique serpentine landscapes. This diminutive annual herb represents one of nature’s most specialized adaptations, thriving in soils that would challenge most other plants. While it may not be the showiest addition ...

Rare plant alert!

Region: Conservation status by state

Status: S1S2Q: Status is uncertain but is somewhere between the following rankings: Uncertain taxonomy: ⚘ 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) ⚘ Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘

Serpentine Monkeyflower: A Rare California Native Worth Protecting

Meet the serpentine monkeyflower (Mimulus brachiatus), a tiny treasure of California’s unique serpentine landscapes. This diminutive annual herb represents one of nature’s most specialized adaptations, thriving in soils that would challenge most other plants. While it may not be the showiest addition to your garden, this rare native offers something far more valuable: a connection to California’s most distinctive ecosystems.

What Makes Serpentine Monkeyflower Special?

Serpentine monkeyflower is an annual forb—essentially a non-woody flowering plant that completes its entire life cycle in a single growing season. As a member of the monkeyflower family, it produces small, cheerful yellow flowers that resemble tiny snapdragons. Don’t expect a dramatic garden display, though; this plant’s beauty lies in its resilience and ecological significance rather than bold visual impact.

What truly sets this species apart is its remarkable adaptation to serpentine soils—those greenish, mineral-rich soils that are toxic to most plants but home to California’s rarest botanical communities.

Where Does It Call Home?

This monkeyflower is a true California endemic, found nowhere else on Earth. Its distribution is limited to specific locations within the state where serpentine soils occur, making it one of California’s most geographically restricted native plants.

A Word of Caution: Rarity Matters

Before you start planning your serpentine monkeyflower garden, there’s something crucial to understand: this plant is extremely rare. With a Global Conservation Status of S1S2Q, Mimulus brachiatus is considered critically imperiled to imperiled, with the Q indicating some taxonomic uncertainty. This means every individual plant matters for the species’ survival.

If you’re passionate about growing this species, please ensure you source seeds or plants only from reputable native plant nurseries that practice ethical collection methods. Never collect seeds from wild populations—these plants need every chance they can get to maintain their genetic diversity and population numbers.

The Challenge of Growing Serpentine Monkeyflower

Here’s where things get interesting (and challenging): serpentine monkeyflower doesn’t just prefer serpentine soils—it requires them. These specialized soils are:

  • High in magnesium and low in calcium
  • Often contain heavy metals that are toxic to most plants
  • Nutrient-poor and well-draining
  • Difficult to replicate in typical garden settings

Growing this plant successfully means recreating these harsh conditions, which is no small feat for the average gardener. You’ll likely need to source genuine serpentine soil or carefully amend your garden soil to mimic these unique conditions.

Climate and Care Requirements

As a California native annual, serpentine monkeyflower is adapted to Mediterranean climate conditions with mild, wet winters and dry summers. It likely thrives in USDA hardiness zones 8-10, matching California’s coastal and foothill regions.

Care tips for the ambitious grower:

  • Provide full sun to partial shade
  • Ensure excellent drainage—these plants hate soggy feet
  • Water sparingly, mimicking natural rainfall patterns
  • Avoid fertilizing, as the plant is adapted to nutrient-poor conditions
  • Allow the plant to complete its life cycle and drop seeds naturally

Supporting Pollinators and Wildlife

Like other monkeyflowers, serpentine monkeyflower likely attracts small native bees and other specialized pollinators. These relationships have evolved over thousands of years, making the plant an important part of California’s native pollinator network, even if its individual contribution seems small.

Is This Plant Right for Your Garden?

Serpentine monkeyflower isn’t for every gardener—or even most gardeners. Consider this plant if you:

  • Are passionate about California native plant conservation
  • Have access to serpentine soils or can create appropriate growing conditions
  • Want to support extremely rare native species
  • Enjoy the challenge of growing specialized plants
  • Are creating a native plant conservation collection

For most native plant enthusiasts, other monkeyflower species like scarlet monkeyflower (Mimulus cardinalis) or sticky monkeyflower (Mimulus aurantiacus) might be more practical choices that still support native ecosystems.

A Living Piece of California’s Natural Heritage

While serpentine monkeyflower may not be the easiest native plant to grow, it represents something irreplaceable: a direct connection to California’s most unique geological and ecological heritage. Every successfully grown plant is a small victory for conservation and a testament to the incredible diversity of California’s native flora.

If you’re up for the challenge and can source plants responsibly, growing serpentine monkeyflower offers the reward of nurturing one of California’s rarest botanical treasures right in your own garden.

Serpentine Monkeyflower

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Scrophulariales

Family

Scrophulariaceae Juss. - Figwort family

Genus

Mimulus L. - monkeyflower

Species

Mimulus brachiatus Pennell - serpentine monkeyflower

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