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clammy azalea, swamp azalea

Habit Shrubs or trees, to 7 m, rhizomatous or not. Subshrubs, shrubs, or trees, multicellular hairs present; bark smooth or furrowed, not flaky (peeling or shredding in Menziesia).
Stems

bark smooth to vertically furrowed, shredding;

twigs sparsely to conspicuously multicellular eglandular-hairy (hairs unbranched), otherwise glabrous or densely unicellular-hairy.

erect to decumbent, sprawling, creeping, trailing, prostrate, or procumbent.

Leaves

deciduous;

petiole usually multicellular eglandular-hairy and unicellular-hairy;

blade ovate to obovate, 2–7(–9) × 1–3(–3.8) cm, ± thin, membranous to chartaceous, margins entire or, sometimes, minutely serrulate, plane, ciliate, eglandular-hairy, apex acute to obtuse, often mucronate, abaxial surface glabrous or densely unicellular-hairy, adaxial surface (lustrous or dull), glabrous or sparsely scattered eglandular-hairy, sometimes also sparsely unicellular-hairy.

deciduous or persistent, usually alternate, sometimes opposite, whorled, or spirally arranged;

petiole usually present;

blade plane or acicular, abaxial groove present or absent.

Inflorescences

3–14-flowered;

bracts similar to bud scales.

axillary or terminal, fascicles, racemes, panicles, capitula, cymes, umbels, corymbs, spikes, or solitary flowers;

perulae present or absent;

bracts much shorter than sepals (sometimes absent).

Pedicels

5–27 mm, stipitate-glandular- or, sometimes, eglandular-hairy, otherwise sparsely to densely unicellular-hairy.

Flowers

opening after leaves, erect to horizontal, slightly to strongly fragrant (most noticeable at night);

calyx lobes 0.5–5 mm, surfaces and margins scattered stipitate-glandular-hairy or, sometimes, eglandular-hairy, often also unicellular-hairy;

corolla white, sometimes pink-tinged or pink (not strongly contrasting with white or greenish to pinkish style or filaments), without blotch on upper lobe, funnelform, 20–58 mm, usually scattered, often conspicuously stipitate-glandular-hairy (hairs continuing in lines up lobes), otherwise sparsely to moderately unicellular-hairy on outer surface, petals connate, lobes 7–21 mm, tube usually ± gradually expanded into lobes, 13–37 mm (equaling or much longer than lobes);

stamens 5, much exserted, ± unequal, 21–65 mm.

bisexual or unisexual, erect or pendulous, usually radially or bilaterally symmetric;

sepals (2-)4-5(-7);

petals absent or (2-)4-5(-7), connate or distinct, corolla deciduous or persistent, campanulate, salverform, rotate, saucer-shaped, funnelform, cylindric, or urceolate, (with pockets holding anthers until they open in some Kalmia), lobes shorter than tube;

intrastaminal nectary disc present;

stamens (2-)5-10;

anthers dehiscent by lateral pores or slits;

ovary (2-)5-10-locular;

placentation axile (parietal distally in Epigaea);

style straight or declinate (curved in Elliottia).

Fruits

capsular, dehiscence usually septicidal, sometimes loculicidal or septifragal, or drupaceous, (dry to fleshy), indehiscent.

Capsules

borne on erect pedicels, 7–20 × 3–7 mm, usually densely stipitate-glandular- and/or eglandular-hairy, otherwise densely unicellular-hairy to ± glabrous.

Seeds

without distinct tails, flattened portion of testa well developed at each end;

testa expanded, dorsiventrally flattened, ± loose.

2-300, distinct, obovoid, ovoid, or ellipsoid to oblong, linear, fusiform, or planoconvex, winged or not.

Floral

bud scales glabrous or densely unicellular-hairy abaxially (sometimes with sharply marked, dark brown band along distal margins), margins unicellular-ciliate or, sometimes, glandular-serrulate.

2n

= 26.

Rhododendron viscosum

Ericaceae subfam. ericoideae

Phenology Flowering spring–summer.
Habitat Acid swamps, bogs, seepage slopes, pocosins, streamheads and baygalls, wet pine flatwoods, moist pine or pine/oak forests, hummocks, shrub balds
Elevation 0-1500 m (0-4900 ft)
Distribution
from FNA
AL; AR; CT; DE; FL; GA; LA; MA; MD; ME; MS; NC; NH; NJ; NY; OK; PA; RI; SC; TN; TX; VA; VT
[WildflowerSearch map]
[BONAP county map]
North America; Mexico; Central America; West Indies (Cuba); s South America; Europe; Asia; Africa; Atlantic Islands; Australia; especially diverse in western Europe and southern Africa
Discussion

Rhododendron viscosum is the most widespread and variable species of sect. Pentanthera and has been divided into as many as four species: R. coryi, R. oblongifolium, R. serrulatum, and R. viscosum in the narrow sense. In addition, minor varieties and forms have been described. Because correlated or geographically coherent sets of character states cannot be discerned within this species, infraspecific taxa are not recognized here (K. A. Kron 1993). Rhododendron viscosum is most closely related to R. arborescens, and possibly also R. atlanticum. Hybrids with R. cumberlandense and R. arborescens are known. Plants with white corollas and a yellow blotch may be the result of hybridization.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera 18, species ca. 1850 (14 genera, 58 species in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 8, p. 471. FNA vol. 8, p. 449. Authors: Gordon C. Tucker, Gary D. Wallace.
Parent taxa Ericaceae > subfam. Ericoideae > Rhododendron Ericaceae
Sibling taxa
R. alabamense, R. albiflorum, R. arborescens, R. atlanticum, R. austrinum, R. calendulaceum, R. canadense, R. canescens, R. catawbiense, R. columbianum, R. cumberlandense, R. eastmanii, R. flammeum, R. groenlandicum, R. lapponicum, R. macrophyllum, R. maximum, R. minus, R. occidentale, R. periclymenoides, R. prinophyllum, R. prunifolium, R. tomentosum, R. vaseyi
Subordinate taxa
Synonyms Azalea viscosa, Azalea oblongifolia, Azalea serrulata, R. coryi, R. oblongifolium, R. serrulatum, R. viscosum var. serrulatum tribe Empetraceae
Name authority (Linnaeus) Torrey: Fl. N. Middle United States, 424. 1824 , Link: Handbuch 1 602. (1829) — (as Ericeae)
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