North America Native Plant

Ragged Rockflower

Botanical name: Crossosoma bigelovii var. glaucum

USDA symbol: CRBIG

Life cycle: perennial

Habit: shrub

Native status: Native to the lower 48 states  

Synonyms: Crossosoma glaucum Small (CRGL8)   

Ragged Rockflower: Arizona’s Resilient Desert Beauty Meet the ragged rockflower (Crossosoma bigelovii var. glaucum), a charming native Arizona shrub that’s perfectly adapted to desert life. While this plant might not be on every gardener’s radar, it deserves serious consideration if you’re looking to create an authentic Southwestern landscape that thrives ...

Rare plant alert!

Region: Conservation status by state

Status: S5T3?Q: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ Uncertain taxonomy: ⚘ 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. ⚘

Ragged Rockflower: Arizona’s Resilient Desert Beauty

Meet the ragged rockflower (Crossosoma bigelovii var. glaucum), a charming native Arizona shrub that’s perfectly adapted to desert life. While this plant might not be on every gardener’s radar, it deserves serious consideration if you’re looking to create an authentic Southwestern landscape that thrives with minimal fuss.

What Makes Ragged Rockflower Special?

This perennial shrub is a true Arizona native, belonging to a small family of plants found only in the American Southwest. The ragged rockflower typically grows as a multi-stemmed woody plant, usually staying under 13-16 feet tall, making it perfect for residential landscapes. The glaucum in its scientific name hints at one of its most attractive features—the bluish-green tint that gives its small, oval leaves a distinctive appearance.

In spring, this unassuming shrub puts on quite a show with delicate white flowers featuring 4-5 petals. These blooms may look simple, but they’re perfectly designed to attract native pollinators, making your garden a haven for local bees and other beneficial insects.

Where Does Ragged Rockflower Call Home?

This variety of Crossosoma bigelovii is native to Arizona, where it thrives in the challenging conditions of the Sonoran Desert. It’s perfectly adapted to extreme heat, intense sun, and minimal rainfall—conditions that would stress many other garden plants.

Why Choose Ragged Rockflower for Your Garden?

Here are the compelling reasons to consider this native beauty:

  • Water-wise wonder: Once established, it requires very little supplemental watering
  • Low maintenance: Thrives on neglect once settled in
  • Native credibility: Supports local ecosystem and wildlife
  • Unique appearance: The bluish-green foliage adds interesting color variation
  • Pollinator magnet: Spring flowers attract beneficial native insects
  • Heat tolerance: Unfazed by scorching desert summers

Perfect Garden Settings

Ragged rockflower shines in:

  • Desert and xeriscape gardens
  • Native plant collections
  • Rock gardens and naturalistic landscapes
  • Low-water demonstration gardens
  • Wildlife-friendly landscapes

Growing Conditions and Care

This Arizona native is refreshingly straightforward to grow if you can provide the right conditions:

Sun Requirements: Full sun is essential—this plant loves intense desert sunshine.

Soil Needs: Well-draining soil is non-negotiable. Sandy or rocky soil that mimics desert conditions works best. Heavy clay or consistently moist soil will likely kill it.

Hardiness: Best suited for USDA zones 9-11, matching its native Arizona habitat.

Water Requirements: Once established (usually after the first year), it’s extremely drought-tolerant. During establishment, provide occasional deep watering, then step back and let nature take over.

Planting and Care Tips

Getting your ragged rockflower off to a good start:

  • Best planting time: Fall or early spring when temperatures are moderate
  • Soil preparation: Ensure excellent drainage—add sand or gravel if needed
  • Initial watering: Water deeply but infrequently during the first growing season
  • Mature care: Step back and enjoy—this plant thrives on benign neglect
  • Pruning: Minimal pruning needed; remove dead or damaged branches as necessary

A Word of Caution

While ragged rockflower makes an excellent choice for appropriate climates, it’s worth noting that this specific variety can be challenging to source. You may need to seek out specialty native plant nurseries or desert plant specialists. Additionally, like many desert natives, it won’t tolerate overwatering or humid conditions—it’s definitely a plant for arid climate gardeners.

The Bottom Line

Ragged rockflower represents the best of native desert gardening—beautiful, resilient, and perfectly adapted to its environment. If you’re gardening in Arizona or similar arid conditions and want a unique native shrub that supports local wildlife while requiring minimal care, this could be your perfect plant. Just remember that success lies in mimicking its natural desert habitat: lots of sun, excellent drainage, and a light hand with the watering can.

For gardeners in other climates, consider exploring native alternatives that offer similar low-maintenance benefits in your specific region. Every landscape benefits from plants that are naturally suited to local conditions!

Ragged Rockflower

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

Rosales

Family

Crossosomataceae Engl. - Crossosoma family

Genus

Crossosoma Nutt. - rockflower

Species

Crossosoma bigelovii S. Watson - ragged rockflower

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