RHODODENDRON, RHODORA, AZALEA (RHODODENDRON SPECIES)
Rhododendrons and azaleas are chiefly ornamental shrubs, grown for their brightly coloured and showy flower clusters and often distinguished by evergreen foliage. They are members of the blueberry family, all of which have potentially toxic leaves and flowers, even though cranberries and blueberries are perfectly safe eating.
Many livestock deaths are attributable to wild species of the blueberry family, such as lambkill and laurel, but human beings have to eat a lot of leaves to get sick. The Delaware Aboriginal people reportedly used laurel tea to commit suicide; it must have taken quite a brew to get fatal effects.
In Nova Scotia, the only native species of rhododendron is Rhodora, the wild rhododendron. All other rhododendrons and azaleas are cultivated ornamentals, which gardeners struggle to help survive our often-severe winters. Heath family species all contain terpenoid toxins in their leaves and stems and should be avoided in teas; and livestock should not graze these plants.
Flowers and leaves of all rhododendrons and azaleas.
Some glycosides, but particularly andromedotoxin, a volatile resin chemically related to turpentine. Luckily, like turpentine, andromedotoxin burns the mouth, which frequently discourages potential victims from consuming dangerous quantities of the leaves.
TYPICAL POISONING SCENARIO
Consumption of leaves and/or quantities of flowers by livestock or children. Even the continual consumption of honey from rhododendron and azalea flowers can be poisonous. This effect has been known since 400 BCE, when honey was a chief source of sweetness in Europe and Asia. Greek soldiers of that era were poisoned by prolonged use of rhododendron honey.
The human digestive tract is capable of breaking down small doses of andromedotoxins into harmless compounds, so human fatalities from eating these plants are rare. However, victims who consume a lot suffer from nausea, vomiting, abdominal upset, and low blood pressure. People who regularly eat affected honey can suffer chronic symptoms of this sort, as well.
RHODODENDRON, RHODORA, AZALEA POISON INFORMATION
Resins and Volatile Oils
Resins and volatile oils are derived mostly from hydrocarbons—chemicals composed of hydrogen, carbon, and oxygen. This group of poisons is very diverse.