North America Native Plant

Rainbow Iris

Botanical name: Iris hartwegii australis

USDA symbol: IRHAA

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Iris hartwegii Baker var. australis Parish (IRHAA2)   

Rainbow Iris: A Rare California Native Worth Knowing About Meet the rainbow iris (Iris hartwegii australis), a mysterious and uncommon native plant that calls California home. If you’ve never heard of this particular iris before, you’re not alone – it’s one of those botanical treasures that flies under the radar, ...

Rare plant alert!

Region: Conservation status by state

Status: S4T3?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ 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 ⚘

Rainbow Iris: A Rare California Native Worth Knowing About

Meet the rainbow iris (Iris hartwegii australis), a mysterious and uncommon native plant that calls California home. If you’ve never heard of this particular iris before, you’re not alone – it’s one of those botanical treasures that flies under the radar, even among seasoned native plant enthusiasts.

What Makes This Iris Special?

The rainbow iris is a perennial forb, which is just a fancy way of saying it’s a non-woody plant that comes back year after year. Unlike shrubs or trees, forbs like this iris have soft, herbaceous stems and store their energy in underground structures to survive through seasons.

This particular iris is actually a variety of Iris hartwegii, and it goes by the scientific synonym Iris hartwegii Baker var. australis Parish. But let’s stick with rainbow iris – it’s much easier to remember!

Where Does It Grow?

The rainbow iris is native to California, where it has adapted to the unique climate and growing conditions of the Golden State. As a true California native, it’s perfectly suited to the Mediterranean-style climate with its wet winters and dry summers.

The Rarity Factor: Why You Should Care

Here’s where things get interesting – and a bit concerning. The rainbow iris has a Global Conservation Status of S4T3?, which essentially means its conservation status is undefined or uncertain. This classification suggests that this plant may face some conservation challenges, and detailed population data might be limited or unclear.

What does this mean for gardeners? If you’re lucky enough to encounter this iris or have the opportunity to grow it, approach with respect and responsibility. This isn’t a plant you’ll find at your local nursery, and that’s probably for good reason.

The Challenge of Growing Rainbow Iris

Unfortunately, detailed growing information for this specific iris variety is quite limited. This lack of cultivation knowledge, combined with its conservation status, presents some real challenges:

  • Growing conditions and care requirements are not well-documented
  • Propagation methods aren’t widely known
  • Its specific role in garden design hasn’t been established
  • Pollinator and wildlife benefits are unclear

A Better Path Forward

Given the uncertainty surrounding this rare iris, most gardeners would be better served by choosing other native California iris species that are:

  • Better understood and documented
  • More readily available from reputable native plant nurseries
  • Proven performers in home gardens
  • Not of conservation concern

Consider looking into other California native irises like Pacific Coast Iris (Iris douglasiana) or Yellow-leaved Iris (Iris chrysophylla), which offer similar native benefits with much better-known growing requirements.

If You Do Encounter Rainbow Iris

Should you come across this rare beauty in the wild or have access to responsibly sourced material, treat it with the respect it deserves. Here are some guidelines:

  • Never collect from wild populations
  • Only obtain plants or seeds from reputable sources with proper collection permits
  • Consider contributing to conservation efforts by reporting sightings to local botanical organizations
  • If you do grow it, share your experiences with the native plant community to help build knowledge

The Bottom Line

While the rainbow iris is undoubtedly a fascinating California native, its rarity and the limited information available make it more of a conservation curiosity than a practical garden choice for most of us. Sometimes the most responsible thing we can do as gardeners is to appreciate these rare plants from a distance and choose better-known native alternatives that can provide similar ecological benefits without the conservation concerns.

That said, if you’re a serious native plant collector with access to responsibly sourced material and a passion for growing rare plants, the rainbow iris could be an intriguing addition to a specialized collection. Just remember – with great rarity comes great responsibility!

Rainbow Iris

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Liliidae

Order

Liliales

Family

Iridaceae Juss. - Iris family

Genus

Iris L. - iris

Species

Iris hartwegii Baker - rainbow iris

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