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Rhododendron viscosum (Swamp azalea)
Vick, Albert F. W.

Rhododendron viscosum (L.) Torr.

Swamp azalea, Clammy azalea, Cory azalea

Ericaceae (Heath Family)

Synonyms: Azalea viscosa, Rhododendron coryi

USDA Symbol: RHVI2

USDA Native Status: Native to U.S.

Clammy azalea is a loose, open, deciduous shrub growing to 12 ft. in width, but averaging only about 5 ft. tall. The leaves, clustered at the end of branches, are 1 1/2–3 1/2 inches long and 5/8–1 1/2 inches wide, deciduous, lustrous, green on both sides, with short stems. The sweet-scented flowers are white, with a lavender tube slightly enlarged at the base, 1 1/4–1 3/4 inches long with 5 narrow, petal-like spreading lobes. The 5 stamens are extended. Fall foliage is orange to maroon.

This typical wetland shrub is sometimes called the Clammy Azalea because of its very sticky corolla. The species name means sticky in Latin. The flowers appear after the leaves. Another white wetland species of more southern distribution, the Smooth Azalea (R. arborescens), has smooth twigs, leaves without hairs, and red stamens. Dwarf Azalea (R. atlanticum), with white or pink fragrant flowers on a shrub 3-4 (90-120 cm) tall, is common in deep and along the coastal plain from southern New Jersey to South Carolina.

 

From the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Shrub
Leaf Retention: Deciduous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Breeding System: Flowers Bisexual
Size Notes: Growing up to 15 feet tall but typically around 5 feet.
Leaf: Green
Autumn Foliage: yes
Fruit: Brown
Size Class: 6-12 ft.

Bloom Information

Bloom Color: White , Pink
Bloom Time: May , Jun , Jul , Aug

Distribution

USA: AL , AR , CT , DC , DE , FL , GA , LA , MA , MD , ME , MS , NC , NH , NJ , NY , OK , PA , RI , SC , TN , TX , VA , VT
Native Distribution: ME to OH, s. to FL & LA
Native Habitat: Swamps; bogs; stream margins
USDA Native Status: L48(N)

Growing Conditions

Water Use: High
Light Requirement: Part Shade
Soil Moisture: Wet
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: Low
Soil Description: Wet soil.
Conditions Comments: This is one of the last azaleas to bloom in spring. It is a variable species with several varieties and forms. Good cultural practices reduce the incidence of disease and insect damage. Flood tolerant.

Benefit

Use Wildlife: Low.
Warning: Rhododendrons contain poisonous substances and should not be ingested by humans or animals. Honey made from flowers also may be toxic. POISONOUS PARTS: All parts. Highly Toxic, May be Fatal if eaten. Symptoms include salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, difficult breathing, progressive paralysis of arms and legs, coma. Toxic Principle: Andromedotoxin. (Poisonous Plants of N.C.)
Conspicuous Flowers: yes
Fragrant Flowers: yes
Attracts: Birds

Value to Beneficial Insects

Special Value to Bumble Bees

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.

Propagation

Description: Combine seeds loosely with sphagnum moss and sprinkle lightly over a 2:1 perlite/peat mixture. Germinate under mist or a plastic tent. Optimum temperatures for germination are 45-50 degrees. Transplant seedlings to acid soil with a high content of orga
Seed Treatment: No pretreatment is necessary.
Commercially Avail: yes

Mr. Smarty Plants says

Native shrub to replace non-native azaleas.
February 10, 2009
I want to replace my two dozen azaleas this spring (I think they're unattractive once the flowers fall off). I like the multiseason characteristics of weigela (midnight wine, W&R), but want to go na...
view the full question and answer

From the National Suppliers Directory

According to the inventory provided by Associate Suppliers, this plant is available at the following locations:

Edge of the Woods Native Plant Nursery - Orefield, PA
LAMTREE FARM - Warrensville, NC
American Native Nursery - Quakertown, PA

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is either on display or available from the following:

Delaware Nature Society - Hockessin, DE

Bibliography

Bibref 996 - Gardening with Native Plants of the South (1994) Wasowski, Sally and Andy Wasowski
Bibref 318 - Native Texas Plants: Landscaping Region by Region (2002) Wasowski, S. & A. Wasowski
Bibref 248 - Texas Wildflowers: A Field Guide (1984) Loughmiller, C. & L. Loughmiller

Search More Titles in Bibliography

Recommended Species Lists

Find native plant species by state. Each list contains commercially available species suitable for gardens and planned landscapes. Once you have selected a collection, you can browse the collection or search within it using the combination search.

View Recommended Species page

Additional resources

USDA: Find Rhododendron viscosum in USDA Plants
FNA: Find Rhododendron viscosum in the Flora of North America (if available)
Google: Search Google for Rhododendron viscosum

Metadata

Record Modified: 2010-04-27
Research By: TWC Staff

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