Native Plants

Slender Arrowgrass

Triglochin concinna

USDA symbol: TRCO19

perennial grass

Lower 48 states: native

If you’re looking to create a thriving wetland garden or restore a natural water feature, meet your new best friend: slender arrowgrass (Triglochin concinna). This understated native perennial might not win any beauty contests, but it’s absolutely essential for anyone serious about wetland gardening in the western United States. Slender ...

Slender Arrowgrass: A Hidden Gem for Wetland Gardens

If you’re looking to create a thriving wetland garden or restore a natural water feature, meet your new best friend: slender arrowgrass (Triglochin concinna). This understated native perennial might not win any beauty contests, but it’s absolutely essential for anyone serious about wetland gardening in the western United States.

What is Slender Arrowgrass?

Slender arrowgrass is a native perennial grass-like plant that belongs to the arrow-grass family (Juncaginaceae). Don’t let the grass in its name fool you – it’s not actually a true grass, but rather a specialized wetland plant that has evolved to thrive in consistently wet conditions. This hardy perennial forms clumps of narrow, linear leaves that emerge directly from the ground, creating a subtle but important presence in wetland ecosystems.

Where Does It Naturally Grow?

This native beauty calls the western United States home, naturally occurring in California, New Mexico, Oregon, and Washington. As an obligate wetland species, it almost always grows in wetlands throughout both the Arid West and Western Mountains, Valleys, and Coast regions.

  • Species observed
  • No observations

Why Plant Slender Arrowgrass?

While slender arrowgrass won’t give you the flashy blooms of a wildflower meadow, it offers something far more valuable for the right garden situation:

  • Authentic wetland restoration: If you’re restoring a natural wetland area or creating habitat, this plant is essential for ecological authenticity
  • Low maintenance: Once established in the right conditions, it requires minimal care
  • Native status: Supporting local ecosystems by choosing plants that naturally belong in your region
  • Wetland functionality: Helps with water filtration and soil stabilization in wet areas

Perfect Garden Settings

Slender arrowgrass isn’t for every garden, but it’s perfect for these specialized situations:

  • Wetland restoration projects
  • Rain gardens and bioswales
  • Pond and stream margins
  • Bog gardens
  • Native plant gardens with wet areas
  • Naturalistic water features

Growing Conditions and Care

The key to success with slender arrowgrass is understanding its one non-negotiable requirement: water, water, water! This obligate wetland plant needs consistently moist to wet soil conditions year-round.

Soil: Thrives in wet, poorly drained soils. Can handle both alkaline and neutral pH levels.

Light: Prefers full sun but tolerates partial shade, especially in hotter climates.

Water: Requires constant moisture – this isn’t a plant that forgives drought!

Hardiness: Suitable for USDA zones 6-9, matching its native range.

Planting and Establishment Tips

Spring is your best bet for planting slender arrowgrass. Here’s how to set it up for success:

  • Choose a naturally wet location or create one with consistent irrigation
  • Plant in groups for a more natural appearance and better establishment
  • Ensure the planting site stays consistently moist during establishment
  • Be patient – like many native wetland plants, it may take time to establish
  • Minimal fertilization needed; wetland plants are adapted to nutrient-poor conditions

Is This Plant Right for Your Garden?

Slender arrowgrass is definitely a specialized plant for specialized situations. Consider it if you have a wet area that needs native plants, are working on wetland restoration, or want to create authentic habitat for local wildlife. However, skip it if you’re looking for ornamental appeal or don’t have consistently wet conditions to offer.

This quiet achiever might not be the star of your garden show, but for the right wetland garden situation, slender arrowgrass is an invaluable native choice that supports local ecosystems while requiring minimal maintenance once established in its preferred soggy conditions.

Triglochin concinna is also known as...

Often we refer to plants by their common names. When shopping for plants the scientific name is the best way to positively identify the plant species you desire. But some plants have more than one name! While it doesn't happen often, nurseries might display one name while you're searching for another. Triglochin concinna is also known as:

Triglochin concinnum Burtt Davy, orth. var. | USDA symbol: TRCO4
Triglochin concinna Burtt Davy var. concinna | USDA symbol: TRCOC2
Triglochin concinnum Burtt Davy var. debile Howell, orth. var. | USDA symbol: TRCOD
Triglochin concinna Burtt Davy var. debilis Howell, orth. var. | USDA symbol: TRCOD2
Triglochin debile Á. Löve & Löve | USDA symbol: TRDE5
Triglochin debilis Á. Löve & Löve, orth. var. | USDA symbol: TRDE9

Why do some plants have more than one name? Over time plant species may be renamed for a few reasons:

  1. Botanists in different regions named the same plant without knowing it had already been classified.
  2. A species was reclassified after scientific advances in, for example, DNA analysis.
  3. Slight variations within a species are sometimes mistakenly identified as entirely new species.

Wetland Status

The rule of seasoned gardeners and landscapers is to choose the "right plant for the right place" — matching plants to their ideal growing conditions, so they'll thrive with less care and fewer inputs. But the simplicity of this catchphrase conceals how tricky plant selection can be if you don't have the right information. While tags on nursery plants list watering requirements, there's more to the story.

Knowing a plant's wetland status can simplify the process by revealing the interaction between plants, water, and soil. You might be surprised to learn that popular landscape plants are wetland species! And what may be a wetland plant in one area, in another it might thrive in drier conditions. The table below gives insight into the preferred growing conditions of this plant throughout its geographical distribution.

Region
Preferred Habitat

Arid West (AZ, CA, CO, ID, MT, NV, NM, OR, TX, UT, WA, WY)

Obligate Wetland

Western Mountains, Valleys, and Coast (AZ, CA, CO, ID, MT, NV, NM, OR, SD, UT, WA, WY)

Obligate Wetland
Wetland Glossary
Obligate Wetland
Facultative Wetland
Facultative
Facultative Upland
Obligate Upland
Almost always occurs in wetlands
Usually occurs in wetlands but may occur in non-wetlands
Can occur in wetlands and non-wetlands
Usually occurs in non-wetlands but may occur in wetlands
Almost never occurs in wetlands

Classification

Group: Monocot
Kingdom: Plantae - Plants
Subkingdom: Tracheobionta - Vascular plants
Superdivision: Spermatophyta - Seed plants
Division: Magnoliophyta - Flowering plants
Class: Liliopsida - Monocotyledons
Subclass: Alismatidae
Order: Najadales
Family: Juncaginaceae Rich. - Arrow-grass family
Genus: Triglochin L. - arrowgrass

Species: Triglochin concinna Burtt Davy - slender arrowgrass

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