The “Bad” Grass List

By Kevin Noon and Cathy Lewis

We currently know of or suspect several grass species as dangers to our dogs. These species have two characteristics of the floret that make them particularly insidious. The basal extension of the lemma (sheath or bract) around the grass floret comes to a very sharp point as the floret matures and dries out at the end of the plants’ growing season. And the lemma is covered with tiny hairs pointing away from the sharp basal point. As the florets mature, they fall off easily. They can be inhaled into the throat or lungs of a dog, swallowed, caught between the toes, become lodged in the fur, or fall into the ear canal. Once attached, the direction of the basal hairs creates a “barbed” effect which keeps the floret from backing out of the fur or tissue. As the animal moves the floret constantly migrates forward pushing the pointed base further into the tissue.

Once inside the tissue these florets have been known to migrate anywhere inside the body including through organs, down the spinal column, through the eyes, and up the limbs. Aside from the damage and infection caused by the migration, some florets carry bacteria that can cause serious infections depending on where they are located.

The following is a list of the most common grasses with these characteristics that dog owners and veterinarians across the country have identified. The worst known hazards are shown in red.  The links provided contain additional information and/or photographs.

Cheatgrass/Downy brome      Bromus tectorum      Photos in site Gallery

http://www.fs.fed.us/database/feis/plants/graminoid/brotec/all.html

http://plants.usda.gov/java/profile?symbol=BRTE

http://www.ubcbotanicalgarden.org/potd/2007/05/bromus_tectorum.php

Ripgut Brome       Bromus rigidus

http://plants.usda.gov/java/profile?symbol=BRDIR

 

Canada Wild Rye    Elymus canadensis    Photos in site Gallery

Photos: http://plants.usda.gov/gallery/pubs/elca4_003_pvp.jpg

http://tenn.bio.utk.edu/vascular/database/vascular-database.asp?CategoryID=Monocots&FamilyID=Poaceae&GenusID=Elymus&SpeciesID=canadensis

Virginia Wild Rye      Elymus virginicus

http://plants.usda.gov/java/profile?symbol=ELVI3

Great photos: http://tenn.bio.utk.edu/vascular/database/vascular-database.asp?CategoryID=Monocots&FamilyID=Poaceae&GenusID=Elymus&SpeciesID=virginicus

Foxtail Barley      Hordeum jubatum     Photos in site Gallery

Awn photo: http://www.ubcbotanicalgarden.org/potd/2005/09/hordeum_jubatum.php

 

Needle and Thread      Stipa comate

http://plants.usda.gov/java/profile?symbol=HECOC8

Western Needlegrass      Stipa occidentalis

http://plants.usda.gov/java/profile?symbol=ACOCC

California Needlegrass      Stipa pulchra      CA only

http://plants.usda.gov/java/profile?symbol=NAPU4

Sleepygrass/Tall Needle grass      Stipa robusta

http://plants.usda.gov/java/profile?symbol=ACRO7

http://www.lycaeum.org/~sputnik/Plants/Images/Stipa.robusta.jpg

Winter Redtop/winter bentgrass/ticklegrass       Agrostis hiemalis or Agrostis hyemalis

http://plants.usda.gov/java/profile?symbol=AGHY

http://www.eeob.iastate.edu/research/iowagrasses/speciespages/AgrosHiema/AgrosHiema.html

Red Three-Awn     Aristida longiseta

http://plants.usda.gov/java/profile?symbol=ARPUL

http://www.agf.gov.bc.ca/range/RangeID/Plants/ArisLong.html

Single-Awn Aristida      Aristida orcuttianas      CA,AZ,NM,TX

http://plants.usda.gov/java/profile?symbol=ARSCO

Oldfield Threeawn      Aristida oligantha

http://plants.usda.gov/java/profile?symbol=AROL

http://www.eeob.iastate.edu/research/iowagrasses/speciespages/AristOliga/AristOliga.html

Nimblewill      Muhlenbergia schreberi

This plant was suggested as problematic by a plant biologist at U of Minnesota. On inspection, it doesn’t appear immediately to have an aggressive awn, but better to provide the information as potential hazard than not.

http://plants.usda.gov/java/profile?symbol=MUSC

http://plants.usda.gov/gallery/pubs/musc_002_php.jpg

http://plants.usda.gov/java/largeImage?imageID=mupa6_001_avd.tif

 

NRCS database (main): http://plants.usda.gov/

Line drawings of various grasses/identification guide: http://www.caf.wvu.edu/~forage/library/cangrass/content.htm

More photographs of many grasses: http://www.invasive.org

 

© Cathy Lewis & Kevin Noon, 2010