Types Of Plants That Are Poisonous When Taken Internally


Bacteria and Algae

Farm ponds and polluted streams sometimes contain toxic bacteria and freshwater algae.  There are records of horses, cattle, hogs, sheep, dogs, and poultry fatally poisoned by drinking from ponds containing dense algal blooms.  Although this source of toxicity is not common in North Carolina, it is still a possibility and should be guarded against.



A number of fungi, particularly certain mushrooms (toadstools), are poisonous to livestock and pets as well as humans.  Although poisonous mushrooms are not treated in this manual, they should not be overlooked as a possibility in cases of animal illness or death.  Only a specialist, however, should attempt to distinguish poisonous from nonpoisonous species of mushrooms.  Other fungi, such as ergot (Claviceps) on various grasses and others in moldy hay, should always be considered when poisoning has occurred.  See Blackwell (1990) for a thorough discussion of poisoning from fungi.


Vascular Plants

The category “vascular plants” includes herbaceous and woody plants – such as ferns, lycopods, horsetails, conifers, and flowering plants – that make up what is generally thought of as the vegetation of an area.

The plants discussed in this manual are all vascular plants and are arranged by family.  Families are ordered more or less by their supposed evolutionary relationships.  However, evolutionary or phylogenetic relationships can be depicted correctly only by a three-dimensional diagram, so any linear sequence such as that in a book is obviously artificial at various points along the sequence.

The 54 families included here are listed in this table with their common names and broad classification: Division (-ophyta), Class (-opsida), Subclass (-idae), and Family (-aceae).


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