DACF Home → Bureaus & Programs → Maine Natural Areas Program → Communities, Plants, and Animals → Rare Plants → Rhododendron viscosum
Rhododendron viscosum (L.) Torr.
- State Rank: S1
- Global Rank: G5
- State Status: Endangered
Habitat: Swamps, thickets and damp clearings. [Hardwood to mixed forest (forest, upland); Forested wetland]
Range: Southwestern Maine to northeastern Ontario, south to South Carolina and Tennessee.
Aids to Identification: Clammy azalea is a much-branched woody shrub belonging to the heath family. The plants are 1-2.5 meters high. Leaves are narrowly ovate (egg-shaped) or oblong-oblanceolate (much longer than broad). After the dark green leaves are fully developed, trumpet-like, white or sometimes pale pink flowers are borne in terminal clusters of four to nine. The plant's name comes from the sticky hairs on the tube of the flower. Rhodora is the only other native azalea (deciduous members of the genus Rhododendron) that occurs in Maine. It has magenta flowers that are stronly zygomorphic and that appear before the leaves.
Ecological characteristics: This understory shrub is found mainly along the coastal plain in swamps, along pond and stream margins, and on wet highlands. It is a late flowering species, in which flowers appear after most other flowering shrubs have gone by. In Maine, it grows in swampy woods containing hemlock, white pine, red spruce, gray or white birch, red maple, speckled alder, maleberry, sheep laurel, and highbush blueberry.
Phenology: Flowers June to July.
Synonyms: Azalea viscosa L.; Rhododendron viscosum (L.) Torr. var. glaucum (Michx.) Gray.
Known Distribution in Maine: This rare plant has been documented from a total of 5 town(s) in the following county(ies): Oxford, Sagadahoc, York.
Reason(s) for rarity: At northern limit of range; not rare south of New England.
Conservation considerations: Maine stands are vulnerable to depredation by over-enthusiastic collectors, not to mention natural factors which can be limiting at the edge of the species' range. Also considered rare in New Hampshire. Known populations are small and subject to the vagaries of small populations like random fluctuations or localized disturbance events.