North America Native Plant

Marsh Phlox

Botanical name: Phlox kelseyi glandulosa

USDA symbol: PHKEG

Life cycle: perennial

Habit: subshrub

Native status: Native to the lower 48 states  

Marsh Phlox: A Rare Idaho Native Worth Protecting If you’ve stumbled across the name marsh phlox in your native plant research, you’ve discovered one of Idaho’s botanical treasures. Phlox kelseyi glandulosa is a perennial wildflower that calls the Gem State home, but don’t expect to find it at your local ...

Rare plant alert!

Region: Conservation status by state

Status: S4T1T3Q: Status is uncertain but is somewhere between the following rankings: Uncertain taxonomy: ⚘ Subspecies or variety is 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) ⚘ 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. ⚘ 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 ⚘

Marsh Phlox: A Rare Idaho Native Worth Protecting

If you’ve stumbled across the name marsh phlox in your native plant research, you’ve discovered one of Idaho’s botanical treasures. Phlox kelseyi glandulosa is a perennial wildflower that calls the Gem State home, but don’t expect to find it at your local nursery anytime soon.

What Makes Marsh Phlox Special

This native beauty belongs to the phlox family and grows as what botanists call a forb – basically a soft-stemmed perennial that dies back to the ground each winter and returns fresh each spring. Unlike its woody cousins, marsh phlox keeps things simple with herbaceous growth that emerges from buds at or below ground level.

Where You’ll Find It (Spoiler Alert: It’s Rare)

Here’s where things get interesting – and a bit concerning. Marsh phlox is currently found only in Idaho, making it one of the state’s endemic species. Its extremely limited geographic range immediately raises red flags for any conservation-minded gardener.

The rarity status tells the whole story: with a Global Conservation Status of S4T1T3Q, this plant exists in a somewhat undefined conservation category, but the limited distribution speaks volumes about its vulnerability.

Should You Grow Marsh Phlox?

This is where we need to pump the brakes a bit. While the idea of growing a rare Idaho native might sound appealing, there are some important considerations:

  • Extremely limited natural populations mean wild collection could harm remaining plants
  • Very little information exists about cultivation requirements
  • Commercial availability is essentially non-existent
  • Habitat preferences and growing conditions remain largely unknown

If you’re absolutely determined to grow this species, any plant material must come from responsibly sourced, ethically propagated stock – never from wild collection.

Better Alternatives for Your Garden

Instead of potentially contributing to the decline of this rare species, consider these more readily available native phlox options that can provide similar garden benefits:

  • Wild Sweet William (Phlox divaricata) for shaded areas
  • Prairie Phlox (Phlox pilosa) for sunny spots
  • Moss Phlox (Phlox subulata) for groundcover needs

The Conservation Message

Marsh phlox serves as a perfect reminder that not every native plant belongs in our home gardens. Sometimes the best way to appreciate and protect a species is to leave it undisturbed in its natural habitat while supporting conservation efforts and choosing more common native alternatives for our landscapes.

If you encounter this plant in the wild during Idaho adventures, consider yourself lucky – you’re seeing something truly special. Take photos, but leave only footprints and take only memories.

Supporting Native Plant Conservation

Rather than seeking out rare species like marsh phlox for your garden, consider:

  • Supporting local native plant societies and conservation organizations
  • Choosing readily available native plants for your landscape
  • Participating in citizen science projects that help monitor rare species
  • Learning to identify and appreciate rare plants in their natural settings

Sometimes the most responsible thing we can do as gardeners is admire from afar and let sleeping rarities lie. Marsh phlox might be beautiful, but it’s far more valuable thriving in its limited Idaho habitats than struggling in our gardens.

Marsh Phlox

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

Solanales

Family

Polemoniaceae Juss. - Phlox family

Genus

Phlox L. - phlox

Species

Phlox kelseyi Britton - Kelsey's phlox

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