cinquefoil
Symptoms: Fever, chills, loss of appetite, headache, nausea, and tremors.
Treatment: Pygmy Bitter Root, Blue Lupine, Black Sagebrush, Jacob's Ladder Phlox, Yarrow, Hoary Balsamroot, Twinflower, Californian Wild Rose, Beard-Tongue Penstemon, Sundial Lupine, Sand Verbena.
Location: Everywhere.
Yellow Monkeyflower
Symptoms: Causes kidney and liver failure with prolonged exposure.
Treatment: Paintbrush, Yarrow.
Location: Western Yellowstone (Geyser Basin, Gibbon Falls, Bechler River).
Prickly Pear Cactus
Symptoms: Painful to eat, spines contain venom known to cause paralysis.
Treatment: None known.
Location: Southern Range, Eastern Yellowstone.
Helianthella
Symptoms: Instant cardiac arrest.
Treatment: None.
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Location: Northern Range (Dunraven Pass).
Elephant Head
Symptoms: Intense stomach upset, and diarrhoea.
Treatment: Groundsel, Paintbrush, Branching Phacelia, Evening Primrose, Hoary Balsamroot, Californian Wild Rose, Beard-Tongue Penstemon.
Location: Western Yellowstone (Geyser Basin).
Monkshood
Alternate Name(s): "Wolf's Bane"
Symptoms: Tingling, numbness of the mouth, nausea, vomiting, laboured breathing, irregular or weakened heart rate, chills, fever, confusion, mania, convulsions, paralysis, and eventual multiple organ failure.
Treatment: Paintbrush, Jacob's Ladder Phlox, Yarrow, Arnica, Californian Wild Rose, Wild Flax, Beard Tongue Penstemon, Sundial Lupine.
Location: Everywhere.
White Geranium
Symptoms: Redness/irritation around the mouth, vomiting, anorexia, depression, and dermatitis at points of contact.
Treatment: Fireweed, Blue Lupine, Arnica, Summer Coralroot, Sticky Geranium, Wild Flax, Sand Verbena.
Location: Everywhere.
Ladies' Tresses (Orchid)
Symptoms: Foaming/frothing at the mouth, seizures, and heart failure.
Treatment: Jacob's Ladder Phlox, Beard Tongue Penstemon.
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Location: Western Yellowstone (Geyser Basin).
Pussytoes
Symptoms: Headache, dizziness, nausea, restlessness.
Additional: Not fatal.
Treatment: Black Sagebrush, Jacob's Ladder Phlox, Evening Primrose, Hoary Balsamroot, Twinflower, Sundial Lupine, Fiddleneck Phacelia, Red Larkspur.
Location: Everywhere.
Sulfur Buckwheat
Symptoms: Irritation of the nose, eyes, throat and lungs, sore throat, runny nose, burning eyes, cough, swollen lungs, difficulty breathing.
Treatment: Mexican White Sagebrush, Black Sagebrush, Cow Parsnip, Hoary Balsamroot, Summer Coralroot, Sticky Geranium, Wild Flax, Green Rabbitbrush.
Location: Everywhere.
Golden Alyssum
Symptoms: Causes excruciating abdominal pain if eaten.
Treatment: Groundsel, Paintbrush, Branching Phacelia, Evening Primrose, Hoary Balsamroot, Californian Wild Rose, Wild Flax, Beard Tongue Penstemon.
Location: Southern Range.