North America Native Plant

Thompson’s Dalea

Botanical name: Psorothamnus thompsoniae var. thompsoniae

USDA symbol: PSTHT

Life cycle: perennial

Habit: shrub

Native status: Native to the lower 48 states  

Synonyms: Dalea thompsoniae (Vail) L.O. Williams (DATH5)   

Thompson’s Dalea: A Rare Native Utah Treasure Worth Protecting Meet Thompson’s dalea (Psorothamnus thompsoniae var. thompsoniae), one of Utah’s most elusive native shrubs. This perennial beauty might not be gracing garden centers anytime soon, but it’s definitely worth knowing about – especially if you’re passionate about native plant conservation. What ...

Rare plant alert!

Region: Conservation status by state

Status: S3?T3?: 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 ⚘ 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. ⚘

Thompson’s Dalea: A Rare Native Utah Treasure Worth Protecting

Meet Thompson’s dalea (Psorothamnus thompsoniae var. thompsoniae), one of Utah’s most elusive native shrubs. This perennial beauty might not be gracing garden centers anytime soon, but it’s definitely worth knowing about – especially if you’re passionate about native plant conservation.

What Makes Thompson’s Dalea Special?

Thompson’s dalea belongs to the pea family and is a true Utah endemic, meaning it calls only the Beehive State home. This multi-stemmed woody shrub typically stays under 13-16 feet tall, making it a manageable size for landscapes – if you could actually find one to plant!

You might also see this plant referenced by its synonym, Dalea thompsoniae, in older botanical texts. But no matter what you call it, this shrub represents something special: a unique piece of Utah’s natural heritage.

Where Does It Grow?

Thompson’s dalea is found exclusively in Utah, making it a true local celebrity in the plant world. Its limited range contributes to its rarity and makes every population precious for maintaining biodiversity.

The Rarity Reality Check

Here’s where things get serious: Thompson’s dalea has a Global Conservation Status of S3?T3?, which signals potential rarity concerns. While the exact status is somewhat undefined, this classification suggests we should treat this plant with extra care and respect.

What this means for gardeners: If you’re lucky enough to encounter Thompson’s dalea in the wild, admire it but don’t disturb it. And if you ever find it available through specialized native plant sources, make absolutely sure it’s been responsibly propagated and not collected from wild populations.

Should You Try to Grow Thompson’s Dalea?

The honest answer? Probably not, and here’s why:

  • It’s extremely rare and poorly understood
  • Commercial availability is essentially non-existent
  • Growing requirements are largely unknown
  • Wild collection would be ecologically harmful

Instead, consider supporting conservation efforts for rare Utah natives or choosing other native dalea species that are better understood and more readily available.

Alternative Native Options

If you’re drawn to the idea of growing native Utah legumes, consider these more available alternatives:

  • Other Psorothamnus species that are less rare
  • Native lupines
  • Local vetch species
  • Native clovers

Supporting Conservation

The best way to help Thompson’s dalea is to support habitat conservation in Utah and organizations working to protect rare native plants. Sometimes the most loving thing we can do for a plant is to let it thrive in its natural habitat while we choose more common natives for our gardens.

Remember, every rare plant tells a story about the unique ecosystems that shaped it. Thompson’s dalea may not be destined for your backyard, but it’s an important reminder of why protecting natural habitats matters for preserving our botanical heritage.

Thompson’s Dalea

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

Fabales

Family

Fabaceae Lindl. - Pea family

Genus

Psorothamnus Rydb. - dalea

Species

Psorothamnus thompsoniae (Vail) S.L. Welsh & N.D. Atwood - Thompson's dalea

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