North America Native Plant

Howell’s Jewelflower

Botanical name: Streptanthus howellii

USDA symbol: STHO

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Howell’s Jewelflower: A Rare Gem for Native Plant Enthusiasts If you’re looking to add something truly special to your native plant garden, Howell’s jewelflower (Streptanthus howellii) might just be the unique treasure you’ve been seeking. This charming perennial wildflower is one of those plants that makes fellow native plant gardeners ...

Rare plant alert!

Region: Conservation status by state

Status: S2S3: Status is uncertain but is somewhere between the following rankings: 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 ⚘

Howell’s Jewelflower: A Rare Gem for Native Plant Enthusiasts

If you’re looking to add something truly special to your native plant garden, Howell’s jewelflower (Streptanthus howellii) might just be the unique treasure you’ve been seeking. This charming perennial wildflower is one of those plants that makes fellow native plant gardeners do a double-take – and for good reason!

What Makes Howell’s Jewelflower Special

Howell’s jewelflower is a delicate herbaceous perennial that belongs to the mustard family. True to its name, this little beauty produces clusters of small, jewel-toned purple to lavender flowers that seem to dance on slender stems. The narrow, often clasping leaves create an elegant backdrop for the blooms, giving the entire plant a graceful, almost ethereal appearance.

A True Western Native

This lovely wildflower is native to the lower 48 states, specifically calling the Pacific Northwest home. You’ll find Howell’s jewelflower growing naturally in California and Oregon, where it has adapted to some pretty unique growing conditions.

Important Conservation Considerations

Here’s where things get serious for a moment. Howell’s jewelflower has a Global Conservation Status of S2S3, which means it’s considered rare and potentially vulnerable. This isn’t a plant you’ll find at your typical garden center, and that’s actually a good thing – it means we need to be thoughtful about how we grow and share it.

If you’re interested in growing this special native, please make sure you source it responsibly from reputable native plant nurseries or conservation organizations. Never collect seeds or plants from wild populations, as this can harm already vulnerable communities of this rare species.

Where Howell’s Jewelflower Shines in Your Garden

This isn’t your typical border perennial – Howell’s jewelflower has some specific preferences that make it perfect for certain garden situations:

  • Rock gardens where its delicate form can be appreciated up close
  • Native plant gardens focusing on Pacific Northwest species
  • Drought-tolerant landscapes that celebrate water-wise gardening
  • Specialty gardens featuring plants adapted to challenging soils

Growing Conditions That Make It Happy

Howell’s jewelflower has evolved to thrive in some pretty specific conditions, particularly serpentine soils – those mineral-rich, challenging soils that many plants can’t handle. In your garden, you can recreate these conditions by focusing on excellent drainage and rocky or sandy soil amendments.

This hardy perennial does best in:

  • USDA hardiness zones 8-10
  • Full sun to partial shade locations
  • Well-draining, rocky, or sandy soils
  • Areas that stay relatively dry once established

Planting and Care Tips

The secret to success with Howell’s jewelflower is thinking lean and mean. This plant doesn’t want rich, fertile soil or regular watering – it actually prefers life on the tough side.

When planting, amend your soil with coarse sand, small gravel, or decomposed granite to improve drainage. If you can get your hands on some serpentine rock chips (available from specialty rock suppliers), even better! Plant in spring after the last frost, and water gently until established, then step back and let nature take over.

Once established, Howell’s jewelflower is remarkably drought-tolerant and requires minimal care. In fact, too much attention – especially overwatering or fertilizing – can actually harm this tough little native.

Supporting Pollinators and Wildlife

Like many members of the mustard family, Howell’s jewelflower attracts small native bees and other pollinators. While it may not be the showiest pollinator plant in your garden, it provides important nectar sources for specialized native insects that have co-evolved with these types of wildflowers.

Is Howell’s Jewelflower Right for Your Garden?

This special native is perfect for gardeners who love the challenge of growing something truly unique and want to support conservation efforts. It’s ideal if you have a spot with challenging, well-draining soil where other plants might struggle, and you appreciate subtle, delicate beauty over bold, flashy displays.

Just remember – with great rarity comes great responsibility. If you decide to grow Howell’s jewelflower, you’re becoming a steward of a vulnerable native species. Source it ethically, grow it with care, and maybe even save seeds to share with other conservation-minded gardeners (following proper guidelines, of course).

Sometimes the most rewarding plants in our gardens are the quiet ones – the species that whisper rather than shout, but have stories worth telling and beauty worth preserving.

Howell’s Jewelflower

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Dilleniidae

Order

Capparales

Family

Brassicaceae Burnett - Mustard family

Genus

Streptanthus Nutt. - twistflower

Species

Streptanthus howellii S. Watson - Howell's jewelflower

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