Poisonous Plants 
Agronomy 105's Weed ID
Common milkweed
Common milkweed was originally cultivated as an ornamental plant because of its attractive, sweet-smelling pink flowers.  This plant can be easily identified because when its stems are broken open they exude a white, milky substance.  Common milkweed will have a poisoning effect primarily on ruminants such as cattle, sheep, goats and horses.
Milkweed will usually not be eaten by livestock unless it is the only plant left in the pasture.  Symptoms of milkweed poisoning include depression, irregular breathing, lowering of body temperature, diarrhea and possibly even death.
The brown seeds of Common milkweed are large, flattened, and can be disseminated by the wind over long distances.