Threadleaf Groundsel, Senecio (Senecio longilobus) Many-stemmed,

evergreen composite. Toxic agent pyrrolizidine

alkaloids. Cattle and horses are about equally sensitive to this plant. Sheep and goats are more resistant.

Riddell Groundsel, Broom Groundsel (Senecio riddellii) Herbaceous, perennial

of sunflower family. Toxic agent pyrrolizidine

alkaloids.

Cocklebur

Coarse, rough, annual weeds.

Toxic agent is carboxyatractyloside, a glycoside causing hypoglycemia. Can poison all classes of livestock.

Inkweed, Thickleaf Drymary (Drymaria pachyphylla) Smooth, hairless, short-

lived annual. The toxic agent is

unknown. Plant poisons cattle, sheep and goats.

Tansy Mustard (Descurainia pinnata)

Annual forb growing to 2’. Single-stemmed, leafy throughout and covered with fine, gray hairs.

Toxic agent is unknown. Large quantities of the plant must be consumed before poisoning occurs. Tansy mustard also accumulates toxic levels of nitrate.