Terrestrial Flora

The Azalea

Description: The azalea is a flowering shrub that blooms in the spring. They have only one blossom per stem and prefer shade, such as living near or under a tree. There are 15 native azalea species on the east coast, and one on the west coast.


The Azalea is well known in southeast North Carolina. Every spring Wilmington holds the North Carolina Annual Azalea festival. It all started in 1948 and over the years has become a celebration of Wilmington's artwork, culture, gardens, and rich history. Check out the official N.C. Azalea festival website:

    1. Kingdom: Plantae, Angiosperms (unranked), Eudicots (unranked),
                        Asterids (unranked)
 2. Order: Ericales
    3. Family: Ericaceae
    4. Genus: Rhododendron
    5. Subgenus: Pentanthera or Tsutsuji

Scientific Name: Rhododendron atlanticum
Common Name: Azalea, Coastal Azalea, dwarf azalea

Distribution Map:
The "Coastal Azalea" is found along the south eastern coastal plain extending northward into Maryland and Delaware. Spreading by underground stems, R. atlanticum can develop into very large colonies of an acre or more in sandy soils. The coastal azalea is easy to propagate, and makes a nice landscape plant in heavier soils which will restrict the spreading habit.


Continue of Habitat/Niche': The azalea or autotroph does not appear to belong in any food web. Azaleas can be poisonous to both animals and humans.The nectar produced from azaleas can be toxic to an animal. Even in Roman times the azalea was known for its harmful affects on humans!
(website: http://www.rhodyman.net/rhodytox.php)


 "The first written account of rhododendrons goes back to the 4th Century B. C. in Greece. It relates to the poisoning of ten thousand soldiers by honey of Rhododendron luteum (Azalea pontica). Rhododendron poisoning has since been confirmed repeatedly. A poisonous compound is found in rhododendron nectar, producing low blood pressure, shock and even death."

Evolutionary Adaptations: One adaptation the azalea has developed, is the ability to grow in acidic soils and mountainous habitats. The azalea can also regenerate very quickly in forests that have been destroyed by fire. This will benefit the azalea, as it will no longer need to compete with taller trees for light. It will continue to receive extensive amounts of light while the forest and canopy come back.

Environmental Impacts and Conservation:
The azalea is subject to various diseases. Some of these diseases occur when temperatures and precipitation patterns change for an area. Some could say this is due to Climate Change, which many believe is caused by humans. Regardless of what causes the change in climate, some azaleas have been affected. Some of the diseases the azalea can catch include: root rot, stunt nematodes, leaf gall, and pedal blight. Twig blight can occur after an extended heat spell and drought. Many of the diseases can be prevented, or fungicides can be used. For more information check out the N.C. State study. http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin16/odin16.htm

Exobasidium leaf gall

The dwarf azalea, or Rhododendron Atlanticum, is endangered in New Jersey and Pennsylvania. It is not listed as endangered in North Carolina.

Growing Conditions:
Water Use: High
Light Requirement: Part Shade
Soil Moisture: Dry
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: None
Soil Description: Well-drained, sandy soil.
Conditions Comments: Good cultural practices reduce the incidence of disease and insect damage

Friends and Foes: The azalea coexists with other plants and trees. It prefers some shade, not full sun. The azalea itself is the predator because of its toxic nectar.