A Diagnostics Tool for Pond Plants and Algae

Yellow Flag

Iris pseudacorus

Non-Native

USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 28 March 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Illustration courtesy of University of Florida/IFAS Center for Aquatic and Invasive Plants. Used with permission.

What is Yellow Flag?

Physical Characteristics

Leaves:

  • Upright
  • Arching at the top
  • Flat
  • Grow from the soil
  • Sword-shaped
  • Thin
  • Pointed
  • 3-4 feet tall

Flowers:

  • Upright
  • 3-4 feet tall
  • Big
  • Showy
  • Yellow in color
  • Many flowers on each stem
  • 3 sepals pointing down
  • 3 small petals
  • 6 large petals
  • Sepals light brownish-purple veined

Fruit:

  • Seed pod
  • 1.5-3 inches long
  • 3 sided
  • Cylinder shaped
  • Green in color
  • Many seeded

Seeds:

  • Flat
  • Brown in color

Stem:

Roots:

  • 3.94-12 inches long

Where Does it Grow?

EDDMapS. 2024. Early Detection & Distribution Mapping System. The University of Georgia – Center for Invasive Species and Ecosystem Health. Available online at http://www.eddmaps.org/; last accessed January 28, 2024.

Non-Native

Yellow flag native to Europe. This plant can be found in marshes, wet savannas, pinelands, shallow water in ditches and in soggy meadows.

Is it Invasive?

Yellow flag is non-native to the United States, and it can be an aggressive invader that can cover large portions of land in a short period of time, and tends to disrupt the ecosystem by pushing the native species out of their habitat.

This plant is not native to North America, but has naturalized in much of the United States. While it is not illegal to possess this plant in Texas, it probably should not be introduced into new water bodies. 

How to Manage This Plant
Plant Glossary