This is Part 3; parts 1 and 2 were in the immediately-previous posts. 

The travelers remarked on the lovely larkspur flowers but quickly learned that wild larkspur was very bad for horses but okay for oxen and that chockcherry was bad for oxen. Animals, being animals, too often just munched away but were too important and valuable not to be watchful of.

The Oregon Trail travelers eventually learned about other plants:

• Western Buttercup – Indians used it to poison arrows
• Snakeweed – toxic to kidneys and liver
• Death Camas – white ones WERE deadly but BLUE ones were okay; only way to tell was when they flowered in spring, a luxury the immigrants did not have.
• Selenium – an element in the soil taken up into the plume grasses which cause digestive problems for the animals.
• Greaseweed – they started seeing these plants about Chimney Rock and quickly learned that it was good/safe for animals to eat in early spring but poisonous in summer.
• Horsebrush – this was toxic in many ways to animals
• Locoweed – there were many kinds of “loco weed”
• Texas Blue Bonnets – very toxic, producing birth defects in both men and animals
• Water Hemlock – growing vigorously along rivers but toxic
• Wild Parsnips – ditto
• Wild Milkweed – ditto

By the time they reached Owyhee County, Idaho, “there was scarcely a train without sick oxen on it” due to the many bad plants in the alkali areas which they couldn’t keep the animals from eating. In the Blue Mountains of Oregon, the journal entries were pretty routine by this point. Little mention is made of plants except poison ivy. “They must have encountered this all along the way but only here is it often mentioned,” Ms. Packard said.  
Following Grandma’s advice that “if you don’t know it don’t eat it,” was sound advice but to hungry people, they had to learn on their own. Children helped show the way!