North America Native Plant

Widecalyx Monkeyflower

Botanical name: Mimulus platycalyx

USDA symbol: MIPL2

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Widecalyx Monkeyflower: A Rare California Gem Worth Protecting Meet the widecalyx monkeyflower (Mimulus platycalyx), a petite but precious California native that’s as charming as its name suggests. This little annual wildflower might not be the showiest plant in your garden, but it packs a big punch when it comes to ...

Rare plant alert!

Region: Conservation status by state

Status: S3?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ 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 ⚘

Widecalyx Monkeyflower: A Rare California Gem Worth Protecting

Meet the widecalyx monkeyflower (Mimulus platycalyx), a petite but precious California native that’s as charming as its name suggests. This little annual wildflower might not be the showiest plant in your garden, but it packs a big punch when it comes to supporting local wildlife and preserving California’s natural heritage.

What Makes This Monkeyflower Special

The widecalyx monkeyflower is a true Californian through and through. This herbaceous annual forb calls only the Golden State home, making it a genuine local treasure. Standing just 2-8 inches tall, it may be small in stature, but it’s big on character with its cheerful yellow blooms that display the classic monkey face pattern that gives all monkeyflowers their whimsical name.

Where You’ll Find It Growing Wild

This rare beauty is naturally found in California’s Sierra Nevada foothills and Central Valley regions. It’s perfectly adapted to the state’s Mediterranean climate and unique soil conditions, having evolved alongside other native California plants for thousands of years.

A Plant Worth Protecting

Here’s something important to know: the widecalyx monkeyflower has a Global Conservation Status of S3?, which means its population status is somewhat uncertain but potentially vulnerable. This makes it even more special to grow in your garden – you’re literally helping to conserve a piece of California’s natural heritage!

If you’re considering adding this plant to your garden, please make sure to source seeds or plants from reputable native plant nurseries that collect responsibly. Never collect from wild populations.

Garden Appeal and Design Uses

While the widecalyx monkeyflower won’t dominate your landscape with bold colors or towering height, it brings subtle charm and ecological value to the right garden settings. Its delicate yellow flowers bloom in spring (March through May), creating a carpet of tiny cheerful faces that seem to smile up at you from the ground.

This plant works beautifully in:

  • Native California wildflower gardens
  • Rock gardens with good drainage
  • Naturalized meadow areas
  • Conservation gardens focused on rare plants
  • Educational gardens showcasing local flora

Growing Conditions and Care

Being a California native, the widecalyx monkeyflower is surprisingly adaptable, but it does have some preferences. It thrives in USDA hardiness zones 8-10 and prefers moist, well-draining soils – think sandy or clay soils that don’t stay waterlogged but don’t dry out completely either.

This little annual appreciates:

  • Full sun to partial shade
  • Moist but well-draining soil
  • Open areas with good air circulation
  • Minimal summer water once established (true to its California roots!)

Supporting Local Wildlife

Don’t let its small size fool you – the widecalyx monkeyflower is a valuable resource for California’s native pollinators. Small native bees and other beneficial insects visit its flowers for nectar and pollen, making it an important piece of the local ecosystem puzzle.

Planting and Care Tips

Since this is an annual plant, you’ll want to let it complete its full life cycle by allowing some flowers to go to seed. This ensures you’ll have plants returning next year and helps maintain genetic diversity in your garden population.

Here are some key tips for success:

  • Start seeds in fall or early spring when temperatures are cool
  • Scatter seeds on prepared soil surface – they need light to germinate
  • Keep soil consistently moist during germination and early growth
  • Reduce watering as plants mature and temperatures warm
  • Allow some plants to set seed for next year’s generation

The Bottom Line

Growing the widecalyx monkeyflower isn’t about creating a showstopper garden display – it’s about participating in conservation, supporting local wildlife, and celebrating California’s unique botanical heritage. If you’re passionate about native plants and want to grow something truly special that few gardeners have in their yards, this little monkeyflower might just be your perfect match.

Just remember to source responsibly and let some plants go to seed each year. Your garden will become a small sanctuary for a rare California treasure, and that’s something to smile about – just like those cheerful monkey faces looking back at you each spring.

Widecalyx 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 platycalyx Pennell - widecalyx monkeyflower

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