American Sweet Flag vs Sitka Alder - TreeTime.ca

American Sweet Flag vs Sitka Alder

Acorus americanus

Alnus alnobetula subsp. sinuata

CUSTOM GROW

CUSTOM GROW

American Sweet Flag
Sitka Alder

American Sweet Flag is a native perennial wetland plant found along shorelines, streams, wet meadows, and marshes. Its extensive rhizome system allows it to spread and stabilise soil, helping maintain the edges of ponds and streams. This dense growth provides cover for small animals and supports overall wetland biodiversity, while the rhizomes and seeds serve as food for small mammals and waterfowl. Cold-hardy and resilient, it is well-suited for ecological restoration, riparian plantings, erosion control, and naturalization projects.

The plant grows in dense clumps with tall, sword-shaped leaves that release a citrus-like scent when bruised. The rhizomes are aromatic, with a spicy, cinnamon-like fragrance that has been used in perfumery and flavouring. In early summer, American Sweet Flag produces a distinctive floral spike (spadix), adding visual interest to wetland plantings.

Sitka Alder is a native deciduous shrub or small tree that often forms dense thickets. Its extensive root system stabilizes slopes and streambanks. Nitrogen-fixing capabilities and nutrient-rich leaf litter improve soil fertility, creating better growing conditions for surrounding plants. These qualities make it especially effective in disturbed or erosion-prone sites.
Often found in moist, high-elevation mountain environments, Sitka Alder also enhances habitat by providing cover and structure in both riparian and upland areas. Birds and small mammals utilize it for nesting, and its seeds serve as a food source.
Note: We use Sitka Alder for Alnus alnobetula subsp. sinuata. This species is also known by many other common names, including Mountain Alder, Green Alder, and others. Please confirm the scientific name to ensure you are ordering the correct plant.

American Sweet Flag Quick Facts

Sitka Alder Quick Facts

Zone: 3a
Zone: 2a
Height: 0.9 m (3 ft)
Height: 5 m (15 ft)
Spread: 0.6 m (2.0 ft)
Spread: 3 m (10 ft)
Light: partial shade, full sun
Light: partial shade, full sun
Moisture: wet
Moisture: wet
Growth rate: fast
Growth rate: medium
Life span: short
Life span: medium
Growth form: upright, colony-forming
Growth form: upright to prostrate, thicket-forming
Spreading: rhizomes - high
Spreading: seed - medium, layering - medium


Foliage: fragrant
Bark: redish-brown to grey, smooth
Flowers: yellow floral spike
Bloom time: spring to summer
Hybrid: no
Hybrid: no
Catkins: no
Catkins: yes


Native to: AB, BC, SK, MB, ON, QC, NS, NB, NL, NT, PE
Native to: AB, BC, YT, NT
Other Names: american sweetflag
Other Names: wavy leaf alder