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 clip_image002the 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