Maryland Native Plants

Acorus americanus – American Sweet Flag

Growing Information

Acorus americanus, or  American sweet flag, is an evergreen and aquatic rush or sedge and is known as an emergent wetland plant. It grows along quiet streambanks in marshes and wetlands, and in other wet open areas. This species thrives in moisture levels ranging from nine inches of standing water to moist garden soils. Sweet flag does not tolerate heavy shade and, for best growth, requires full sun. To grow in standing water, plant rhizomes in either the soil along the edge of the water or in containers in the shallow water.

Habit

American Sweet Flag spreads via rhizome at a moderate speed and reaches 3 to 4 feet tall at maturity.  The foliage It is often white at the base, with or without a reddish or pinkish tinge. The leaves are usually green at the tops, and arise directly from the rhizomes and sheath into each other at the base. Additionally, the blades have 2-6 raised veins and a swollen center when viewed in cross-section. The foliage has a citrus-like, spicy, aromatic quality when bruised, and can be used to flavor beer. The flowers are inconspicuous and 1-3 inches long. They appear in the spring and early summer. These flowers are arranged on a lateral spadix (a thickened, fleshy axis), and the fertilized flowers produce berries which attract a variety of waterfowl.

Fast Facts

This plant is protected as a state endangered species in Pennsylvania; additionally, it is rare-to-extinct and decreasing at the southern boundary of its range (Virginia).

Sweet Flag is commonly found in areas that used to be home to Native American villages or camping sites – it is very likely that trade and cultivation by Native Americans led to the broad North American distribution of this rush.

The genus name, Acorus, comes from the Greek word for “pupil,” likely influenced by of the use of the plant to treat eye inflammation.

Plant Information

Common Name: American Sweet Flag

Type: Rush or Sedge

Family: Acoraceae

Height: 2.00 to 3.00 feet

Spread: 2.50 to 3.00 feet

Root System: Rhizomes with fibrous roots, will form colonies

Bloom Time: June to July

Bloom Description: Yellow

Sun: Full sun to part shade

Water: Wet

Maintenance: Low

Suggested Use: Water Plant, Naturalize, Rain Garden

Flower: Insignificant

Tolerate: Deer resistant, Erosion, Wet Soil

(Information from iNaturalist and North Carolina Extension)