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Knotgrass

Paspalum distichum

Last reviewed: September 2026

Knotgrass (Paspalum distichum)
Photo: (c) Hannah Rogers, some rights reserved (CC BY)

Toxicity unknown

Knotgrass (Paspalum distichum) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

The USDA PLANTS Database (opens in new tab) does not flag Knotgrass as toxic to livestock.

Light

full sun

Water

high

Size

4"–24" H × 12"–36" W

Bloom

Jun, Jul, Aug, Sep

Native to

AL, AR, AZ, CA and 22 more states

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.

Find rebates in your area

Browse plants for this ecoregion

Coast RangeMarine West Coast ForestSierra NevadaCentral California Foothills and Coastal MountainsCentral California ValleySouthern California MountainsNorthwestern Forested MountainsNorth American DesertsCentral Basin and RangeMojave Basin and RangeArizona/New Mexico MountainsChihuahuan DesertsHigh PlainsSouthwestern TablelandsCentral Great PlainsCross TimbersEdwards PlateauTexas Blackland PrairiesEast Central Texas PlainsWestern Gulf Coastal PlainSouth Central PlainsEastern Temperate ForestsPiedmontMiddle Atlantic Coastal PlainSoutheastern PlainsInterior PlateauMississippi Alluvial PlainMississippi Valley Loess PlainsSouthern Coastal PlainSouthern Florida Coastal PlainMadrean ArchipelagoSonoran Basin and RangeSouthern California/Northern Baja Coast

Knotgrass is a low-growing native perennial that spreads by runners to form dense mats. It produces small seed heads from summer through early fall and thrives in wet conditions. This grass is commonly found in marshy areas and along pond edges.

In an HOA neighborhood

Knotgrass takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.

Works well in: backyard only.

  • Aggressive spreading habit can appear uncontrolled
  • High water requirements may conflict with water-wise landscaping preferences
  • Can develop patchy or weedy appearance

Wildlife value

The seed heads provide food for waterfowl and songbirds. As a native grass, it offers nesting material and habitat for small wildlife.

Common questions

How much sun does Knotgrass need?
Knotgrass grows best in full sun conditions.
When does Knotgrass bloom?
Knotgrass blooms in June, July, August, and September.
Where is Knotgrass native?
Knotgrass (Paspalum distichum) is native to AL, AR, AZ, CA and 22 more states, per vouchered herbarium specimen records and regional native plant society lists.
Is Knotgrass toxic to livestock?
The USDA PLANTS Database does not flag Knotgrass as toxic to livestock.
Is Knotgrass HOA-friendly?
Knotgrass takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

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