North America Native Plant

Sulphur Marsh Marigold

Botanical name: Caltha leptosepala leptosepala var. sulfurea

USDA symbol: CALES4

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Sulphur Marsh Marigold: A Rare Mountain Gem for Specialized Gardens If you’re searching for a truly unique native wildflower that’s as rare as it is beautiful, meet the sulphur marsh marigold (Caltha leptosepala var. sulfurea). This isn’t your typical garden center find – it’s a specialized mountain treasure that brings ...

Rare plant alert!

Region: Conservation status by state

Status: S5T2T3: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is 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) ⚘ Subspecies or variety is 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. ⚘ 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. ⚘

Sulphur Marsh Marigold: A Rare Mountain Gem for Specialized Gardens

If you’re searching for a truly unique native wildflower that’s as rare as it is beautiful, meet the sulphur marsh marigold (Caltha leptosepala var. sulfurea). This isn’t your typical garden center find – it’s a specialized mountain treasure that brings a touch of alpine magic to the right garden setting.

What Makes This Plant Special?

The sulphur marsh marigold is a perennial forb, which simply means it’s a non-woody flowering plant that comes back year after year. As part of the buttercup family, it shares that characteristic bright, cheerful bloom that can light up any garden space where it’s happy.

This particular variety stands out with its distinctive sulphur-yellow flowers – a beautiful twist on the more common white marsh marigolds you might encounter in the wild.

Where Does It Call Home?

This native beauty has a pretty exclusive address – you’ll find it naturally growing in Idaho and Montana. It’s perfectly adapted to the challenging conditions of mountain environments, making it a true regional specialist.

The Conservation Reality Check

Here’s something important to know: the sulphur marsh marigold has a Global Conservation Status of S5T2T3, which indicates it’s quite rare. This means if you’re considering adding it to your garden, you’ll want to be extra thoughtful about sourcing. Only purchase from reputable native plant nurseries that can guarantee their plants are ethically propagated, not collected from wild populations.

Is This Plant Right for Your Garden?

Let’s be honest – this isn’t a plant for everyone or every garden. The sulphur marsh marigold is best suited for gardeners who:

  • Live within or near its native range
  • Have experience with specialized alpine or mountain plants
  • Can provide consistently moist to wet soil conditions
  • Are committed to conservation-minded gardening

Garden Design Ideas

When grown successfully, sulphur marsh marigold works beautifully in:

  • Native plant gardens focused on regional flora
  • Rain gardens or bog gardens with consistent moisture
  • Alpine or rock gardens with adequate water
  • Naturalized areas that mimic mountain meadow conditions

Growing Conditions and Care

Like many mountain natives, this plant has specific needs that reflect its natural habitat. While detailed cultivation information is limited due to its rarity, we can infer from its natural growing conditions that it likely prefers:

  • Consistently moist to wet soils
  • Good drainage despite moisture needs
  • Cooler temperatures typical of mountain environments
  • Partial shade to full sun exposure

Given its native range in Idaho and Montana, it’s likely hardy in USDA zones 3-6, though specific zone information for this variety isn’t well-documented.

The Bottom Line

The sulphur marsh marigold is a plant for the dedicated native gardener who appreciates rarity and is committed to conservation. While it’s not the easiest plant to grow or find, it offers the reward of supporting a rare native species while adding a unique splash of mountain beauty to the right garden.

If you’re not in its native range or don’t have the specific conditions it needs, consider supporting conservation efforts for this species in other ways, or explore other native Caltha species that might be better suited to your local conditions.

Remember: with rare plants like this one, every garden that successfully grows them becomes a small sanctuary, helping ensure these botanical treasures continue to exist for future generations to enjoy.

Sulphur Marsh Marigold

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

Ranunculaceae Juss. - Buttercup family

Genus

Caltha L. - marsh marigold

Species

Caltha leptosepala DC. - white marsh marigold

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