North America Native Plant

Heartleaf Suncup

Botanical name: Camissonia cardiophylla robusta

USDA symbol: CACAR2

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Oenothera cardiophylla Torr. ssp. robusta P.H. Raven (OECAR)   

Heartleaf Suncup: A Rare California Native Worth Protecting Meet the heartleaf suncup (Camissonia cardiophylla robusta), a charming but elusive member of California’s native plant community. This little-known wildflower might not be the first plant that comes to mind when planning your garden, but it represents something special in the world ...

Rare plant alert!

Region: Conservation status by state

Status: S3S4T2?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ 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) ⚘ 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 ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Heartleaf Suncup: A Rare California Native Worth Protecting

Meet the heartleaf suncup (Camissonia cardiophylla robusta), a charming but elusive member of California’s native plant community. This little-known wildflower might not be the first plant that comes to mind when planning your garden, but it represents something special in the world of native plants – a rare gem that tells the story of California’s unique botanical heritage.

What Makes Heartleaf Suncup Special?

The heartleaf suncup belongs to the evening primrose family and is classified as a forb – essentially an herbaceous flowering plant without woody stems. What sets this particular variety apart is right there in its name: robusta suggests this is a more vigorous form of the heartleaf suncup species, though detailed information about this specific subspecies remains limited in cultivation circles.

This plant can grow as either an annual or perennial, giving it flexibility in different growing conditions. You might also see it referenced by its scientific synonym, Oenothera cardiophylla Torr. ssp. robusta P.H. Raven, in older botanical references.

Where Does It Call Home?

Heartleaf suncup is a true California native, found exclusively within the Golden State’s borders. As a plant species native to the lower 48 states, it represents the kind of botanical treasure that makes California’s flora so distinctive and diverse.

A Word About Rarity

Here’s where things get important for any gardener considering this plant: heartleaf suncup carries a conservation status of S3S4T2?, which indicates some level of rarity or conservation concern. While the exact meaning of this status is undefined in available resources, the designation suggests this isn’t your typical garden center find.

What this means for you: If you’re interested in growing heartleaf suncup, it’s crucial to source it responsibly. Never collect from wild populations, and only obtain plants or seeds from reputable native plant nurseries that can verify their material comes from ethical, sustainable sources.

Should You Grow Heartleaf Suncup?

The honest answer is: it depends on your gardening goals and commitment level. This plant is best suited for:

  • Specialized native plant gardens focused on California flora
  • Conservation-minded gardeners working to preserve rare species
  • Educational gardens or botanical collections
  • Gardeners with experience growing uncommon natives

The Growing Challenge

Here’s where we hit a bit of a roadblock: detailed cultivation information for Camissonia cardiophylla robusta specifically is quite limited. This lack of readily available growing guides actually reinforces its status as a specialized plant rather than a mainstream garden choice.

What we do know is that as a California native forb, it likely prefers conditions similar to its natural habitat, though without specific data on soil preferences, water needs, or hardiness zones, successful cultivation would require some experimentation and possibly consultation with native plant specialists.

Better Alternatives for Most Gardens

If you’re drawn to California natives in the evening primrose family but want something with more established cultivation guidance, consider these more widely available alternatives:

  • Desert evening primrose (Oenothera deltoides) for drought-tolerant gardens
  • Beach evening primrose (Camissonia cheiranthifolia) for coastal areas
  • Other Camissonia species with better-documented growing requirements

The Bottom Line

Heartleaf suncup represents the fascinating complexity of California’s native plant world – beautiful, unique, and deserving of conservation attention. While it may not be the right choice for every garden, it serves as a reminder of why protecting native plant diversity matters.

If you do choose to grow this rare native, approach it as a conservation effort rather than just another garden addition. Source responsibly, document your growing experiences, and consider sharing your successes with native plant organizations to help build the knowledge base for this special California endemic.

Sometimes the most rewarding plants aren’t the easiest ones to grow – they’re the ones that connect us to the irreplaceable natural heritage of our region.

Heartleaf Suncup

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

Myrtales

Family

Onagraceae Juss. - Evening Primrose family

Genus

Camissonia Link - suncup

Species

Camissonia cardiophylla (Torr.) P.H. Raven - heartleaf suncup

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