Rhododendron 
Severe colic, diarrhea
Don't picket horses near shrubs

Labrador tea 
Severe colic, diarrhea
Edges of meadows at high mountain elevations

Azalea
Severe colic, diarrhea
Don't picket horses near shrubs

Mountain laurel
Severe colic, diarrhea
Don't picket horses near shrubs

Death camas
Colic, frothing at the mouth,
convulsions.
Meadows and open slopes in the late Spring and early Summer.