Rhododendron
The
plant rhododendron belongs to the family Ericaceae which also includes the
Heath, and there are about eight-hundred fifty species which grow worldwide
(Turner and Szczawinski, 171-2). The Heath family is a large one with so many
species, all of the poisonous species fall into two of its subfamilies, one of
which is the rhododendron. These cultivated plants occur naturally in temperate
regions of the northern hemisphere and in the mountains of Southeast Asia. They
are located in the Himalayas with seven-hundred species, southwest China, Burma,
and in New Guinea with over three-hundred species (Turner and szczawinski, 172).
It has been popular as ornaments in gardens and has led to a major horticultural
industry with its widely uses in landscaping. There are twenty-seven species
native to North America, (Turner,172) and is the state plant of Washington. This
specific plant is called R. macrophyllum or the Pacific rhododendron (Pojar and
Mackinnon, 61). It forms a shrub layer in forests ranging from shoreline pine
groves to stands of Douglas-fir and western Hemlock up in the mountains. Usually
they are located everywhere from homes to freeway sides and also in the forests.
The rhododendron shows a great variety in size, habit, and flower color, colors
from white to pink, dark-purple, yellow, red, and orange (McKenzi,1). They range
from small shrubs to small trees with evergreen leaves that are leathery. The
leaves are short stalked, simple, and alternate, and the flowers are large,
bell-shaped, and born in dense clusters. They are best grown on acidous soil
with a ph of 4.5 and 6.5, included with lots of moisture and organic material
(McKenzie, 3). The leaves, flowers, pollen, and nectar of many rhododendron
species contain several toxins (Kingsbury, 50). These toxins are called
grayanotoxins or andromedotoxin, a resinoid carbohydrate (Kingsbury, 51). It is
prevalent in the flower nectar, and has caused poisoning of bees and the honey
produced. The symptoms are similar to both humans and all animals. The human
cases are that in which children chew the leaves and get the poison in their
system, or when people drink tea made from the honey and plant (Abrahams, 2). It
has been reported that animals clip the leaves for boredom or when they get
hungry, as food is short (U.S food and drug admin., 3). The rhododendron is a
beautiful plant which lies outside homes for decorations. People should become
more aware of its toxicity and should take precautions when handling them.
Grayanotoxin The plant rhododendron contains several toxins called grayanotoxins.
Other well known but former names are rhodotoxin, andromedotoxin, and
acetylandrome (U.S. food and drug admin., 1). They are included in almost all of
the species rhododendron. The name of the disease is honey intoxication, which
is caused by the consumption of honey produced (Abrahams 1). The grayanotoxins
cause this intoxication, and the specific toxins vary with the plant species.
Other names associated with this disease is rhododendron poisoning, mad hone
intoxication or grayanotoxin poisoning. (U.S food and drug admin., 1) The
poisoning results from the ingestion of grayanotoxin contaminated honey. The
other ways that it can get into your system is if you consume plant parts. Every
part of the plant is poisonous, the flowers, nectar, honey, and especially the
leaves, which contain more. In humans, symptoms of poisoning occur six hours
after a dose. These symptoms include salivation, vomiting, very low blood
pressure, loss of coordination, muscular weakness, slow and irregular heartbeat,
and comas, followed by death in extreme cases. (U.S. FDA,2) All organisms such
as animals and humans are affected in the same way. The treatments are to induce
vomiting, or perform gastric lavage, replace fluids and maintain electrolyte
balance, monitor heart beat, blood pressure and breathing. Even though the cases
reported have been rare, people still should become aware of this toxin. House
pets eat the plants, children do also, so they should be taught to stay away
from these plants.
