North America Native Plant

Hall’s Madia

Botanical name: Harmonia hallii

USDA symbol: HAHA11

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Madia hallii D.D. Keck (MAHA)   

Hall’s Madia: A Rare California Native Worth Protecting If you’re passionate about preserving California’s unique botanical heritage, Hall’s madia (Harmonia hallii) might just capture your gardening heart. This little-known annual forb represents the kind of native plant that makes California’s flora so special—and so worth protecting. What Makes Hall’s Madia ...

Rare plant alert!

Region: Conservation status by state

Status: S2?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ 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) ⚘

Hall’s Madia: A Rare California Native Worth Protecting

If you’re passionate about preserving California’s unique botanical heritage, Hall’s madia (Harmonia hallii) might just capture your gardening heart. This little-known annual forb represents the kind of native plant that makes California’s flora so special—and so worth protecting.

What Makes Hall’s Madia Special?

Hall’s madia is a true California native, found exclusively within the Golden State’s borders. As an annual forb, this plant completes its entire life cycle in just one growing season, making it a fascinating addition to gardens focused on native biodiversity. The botanical world also knows this plant by its synonym, Madia hallii, which you might encounter in older botanical references.

What sets this plant apart isn’t just its California heritage—it’s also its rarity. Hall’s madia carries a Global Conservation Status of S2?, indicating that its conservation status needs further definition but suggests it may be quite uncommon in the wild.

Where Does Hall’s Madia Grow?

This native beauty calls California home, though specific distribution details within the state remain part of what makes this plant so mysterious and special. Its limited range makes it a true California endemic—a plant found nowhere else on Earth.

Should You Grow Hall’s Madia?

Here’s where things get interesting for the conservation-minded gardener. While we’d love to encourage everyone to grow more native plants, Hall’s madia’s potential rarity status means you’ll want to be extra thoughtful about how you approach adding it to your garden.

Important considerations:

  • Only source seeds or plants from reputable native plant societies or nurseries
  • Never collect from wild populations
  • Consider this plant as part of a broader native plant conservation effort
  • Focus on creating habitat that could support this and other native annuals

Growing Hall’s Madia: What We Know

Here’s the honest truth: cultivation information for Hall’s madia is quite limited, which isn’t uncommon for rare native plants that haven’t entered mainstream horticulture. As an annual forb, it likely shares some characteristics with other California native annuals, but specific growing requirements remain largely undocumented.

What we do know:

  • It’s an annual, so it will complete its life cycle in one season
  • As a forb, it’s a non-woody plant that likely produces flowers
  • Being California native, it’s adapted to the state’s Mediterranean climate patterns

The Bigger Picture: Why Rare Natives Matter

Plants like Hall’s madia represent irreplaceable pieces of California’s natural heritage. Even if we can’t provide detailed growing guides, supporting research and conservation efforts for rare natives like this one helps preserve the incredible diversity that makes California’s flora world-renowned.

If you’re interested in growing Hall’s madia, we strongly recommend connecting with local native plant societies, botanical gardens, or conservation organizations. They may have additional insights into cultivation requirements and can help ensure any plants you grow contribute positively to conservation efforts rather than putting wild populations at risk.

Alternative Native Options

While you’re exploring the possibility of growing Hall’s madia, consider incorporating other California native annuals that are better understood and more readily available. These can help create the kind of diverse native plant community where rare species like Hall’s madia might eventually thrive.

Remember, every native plant you grow—whether common or rare—contributes to supporting local ecosystems and preserving California’s unique natural heritage for future generations.

Hall’s Madia

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

Asterales

Family

Asteraceae Bercht. & J. Presl - Aster family

Genus

Harmonia B.G. Baldw. - tarweed

Species

Harmonia hallii (D.D. Keck) B.G. Baldw. - Hall's madia

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