Poisonous plants may be divided into two groups: A. Plants which if taken internally either cause irritation or poison the blood. B. Skin irritants. The majority of the plants in the first group are more harmful to farm animals than to human beings. In the second group the reverse is true.

A. Internally Poisonous:

Aconitum napellus Monkshood

Amanita muscaria Mushroom

Amanita phalloides Mushroom

Arisaema triphyllum Jack-in-the-pulpit

Atropa belladonna Deadly Night-shade

Cicuta maculata Cowbane

Conium maculatum Poison Hemlock

Datura stramonium Jamestown Weed

Delphinium geyi Larkspur

Helleborus niger Christmas Rose

Kalmia angustifolia Sheep Laurel

Kalmia latifolia Mountain Laurel

Lolium temulentum

Darnel Oxytropus lambertini

Slender Loco-weed Passiflora incarnata

Passion Flower Prunus serotina (leaves)

Wild Black Cherry Veratrum viride

Green Hellebore Xylorrhiza parryi

Woody Aster

Zygadenus intermedius Death Camas

B. Skin Irritants:

Primula obconica Hairy Primula

Rhus radicans Poison Ivy

Rhus toxicodendron Poison Oak

Rhus vernix Poison Sumac

Stipa spartea (skin irritant for animals only) Porcupine Grass