While there are many that view the goat as a browser that will thrive when it eats just about anything, there are many things that can kill a goat. Some poisonous plants are ingested by accident, while browsing, but a major reason for the toxic poisoning of goats comes as a result of starvation.

As when any toxic plant is consumed, it is the size of the dose, and the poison present in the plant that will determine whether the animal lives or dies. The following list is devoted to the caprine species, and to many of the plants out there that can kill them. It is a fairly comprehensive list of plants commonly found in areas with goats, but may not be 100% complete.

Alkaloid Containing Plants
Any of a large class of organic, nitrogen-containing ring compounds that have a bitter taste, that are usually water-insoluble and alcohol-soluble, that form water-soluble salts, and usually exhibit pharmacological action, as nicotine, morphine, or quinine. 
Click here for list of plants...

Cyanogenetic Containing Plants
These plants are usually deadly when damaged or frozen.
Click here for list of plants...

Glucosides - Glycosides Containing Plants
Any of the class of compounds that yield a sugar and a noncarbohydrate upon hydrolisis.

Plants That Cause Mechanical Injury
Some plants and shrubs have physical characteristics that would be injurious to animals - thorned plants as an example. Certainly some thorned and spiked plants may be eaten but once they reach the palate, punctures and tears can occur internally which cause a great degree of injury. Also, certain plants are known to 'twine' or 'bind' causing great intestinal difficulties.

Saponin Containing Plants
Any of a group of amorphous glucosidal compounds of steroid structure, characterized by an ability to form emulsions and to foam in aqueous solutions, and used as detergents.
Click here for list of plants...

Photosensitizing Plants
This type of plant will cause a reaction whereas the ingredients interact with light. An animal ingesting such a plant is susceptible to sunburn, heat related illnesses, etc. Not all photosensitizing are considered extremely harmful, however, dependent upon climatic conditions/light, this class of plants can do great damage if the animal is not monitored.
Click here for list of plants...

Tannic Acid Containing Plants
An interesting category.  Most commonly found in Oak leaves, however there is the belief that fresh, green oak leaves are soothing to sick goats.

Resin Containing Plants
This area is also under research since it has been a common practice for many goat owners to feed their discarded Christmas trees to their goats. Apparently this is not such a good idea as while it may not produce immediate, noticeable results, it can be a cause of abortions months later.