North America Native Plant

Ragged Marsh-elder

Botanical name: Hedosyne ambrosiifolia

USDA symbol: HEAM11

Life cycle: annual

Habit: subshrub

Native status: Native to the lower 48 states  

Synonyms: Iva ambrosiifolia (A. Gray) A. Gray (IVAM)  âš˜  Iva ambrosiifolia (A. Gray) A. Gray ssp. lobata (Rydb.) R.C. Jacks. (IVAML2)   

Ragged Marsh-Elder: A Mysterious Native Annual Worth Knowing If you’ve stumbled across the name ragged marsh-elder in your native plant research, you’re probably scratching your head right about now. Don’t worry – you’re not alone! Hedosyne ambrosiifolia is one of those plants that seems to fly under the radar, even ...

Ragged Marsh-Elder: A Mysterious Native Annual Worth Knowing

If you’ve stumbled across the name ragged marsh-elder in your native plant research, you’re probably scratching your head right about now. Don’t worry – you’re not alone! Hedosyne ambrosiifolia is one of those plants that seems to fly under the radar, even among native plant enthusiasts. But sometimes the most interesting discoveries come from the least expected places.

What Exactly is Ragged Marsh-Elder?

Ragged marsh-elder is a native annual forb that calls the American Southwest home. As an annual, this plant completes its entire life cycle in just one growing season – sprouting, growing, flowering, setting seed, and dying all within a year. It’s classified as a forb, which is botanist-speak for a non-woody flowering plant that isn’t a grass.

You might also see this plant listed under its former scientific names, including Iva ambrosiifolia, which gives us a clue about its botanical family connections.

Where Does It Grow?

This southwestern native has carved out its niche across three states: Arizona, New Mexico, and Texas. It’s perfectly adapted to the unique growing conditions of this region, having evolved alongside other desert and semi-arid plants over thousands of years.

The Challenge: What We Don’t Know

Here’s where things get interesting – and a bit frustrating for curious gardeners. Ragged marsh-elder is somewhat of a botanical mystery when it comes to cultivation information. Unlike popular natives that have been extensively studied and grown, this species has limited documented information about:

  • Specific growing requirements
  • Mature size and growth habits
  • Pollinator relationships
  • Seed collection and propagation methods
  • Garden performance and care needs

Should You Grow Ragged Marsh-Elder?

The honest answer? It’s complicated. While this native plant undoubtedly has ecological value in its natural habitat, the lack of cultivation information makes it a challenging choice for home gardeners. Without knowing its specific needs, growth habits, or even how to successfully start it from seed, you’d essentially be conducting your own gardening experiment.

If you’re drawn to native annuals from the Southwest, you might consider better-documented alternatives like:

  • Desert marigold (Baileya multiradiata)
  • Ghost plant (Graptopetalum paraguayense)
  • Desert lupine (Lupinus sparsiflorus)

For the Adventurous Gardener

If you’re still intrigued by ragged marsh-elder despite the unknowns, here’s what we can reasonably assume based on its native range:

  • It likely prefers well-draining soil
  • It’s probably adapted to hot, dry conditions
  • It would likely thrive in USDA zones 8-10
  • It may require little to no supplemental watering once established

The Bigger Picture

Sometimes the plants we know least about are the ones that need our attention most. Ragged marsh-elder represents countless native species that exist in the botanical background – ecologically important but horticulturally overlooked. While we can’t recommend it as a reliable garden choice right now, its very existence reminds us how much we still have to learn about our native flora.

If you’re passionate about southwestern natives and have experience with experimental gardening, ragged marsh-elder might just be your next research project. Who knows? You might be the one to unlock its garden potential and share that knowledge with the rest of us plant nerds.

Until then, we’ll keep this mysterious annual on our plants to watch list – because every native species has a story worth telling, even if we’re still figuring out what that story is.

Ragged Marsh-elder

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

Hedosyne Strother - marsh-elder

Species

Hedosyne ambrosiifolia (A. Gray) Strother - ragged marsh-elder

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