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early azalea, election-pink, hoary azalea, roseshell azalea

Habit Shrubs, to 3(–5) m, usually not rhizomatous. 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 scattered, multicellular eglandular-hairy (hairs unbranched), otherwise densely to sparsely 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, 3–9 × 1.2–3.7 cm, thin, membranous, margins entire, plane, conspicuously ciliate, eglandular-hairy (hairs ascending away from margins), apex acute to obtuse, often mucronate, abaxial surface sparsely to densely unicellular-hairy, sometimes also eglandular-hairy, adaxial surface usually sparsely unicellular-hairy, sometimes glabrous, often also scattered eglandular-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

4–13-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

5–26 mm, usually stipitate-glandular-hairy, or, sometimes, also eglandular-hairy, otherwise sparsely to moderately unicellular-hairy.

Flowers

opening before or with leaves, erect to horizontal, fragrant (spicy-scented);

calyx lobes 0.5–4 mm, surfaces and margins scattered stipitate-glandular- and/or eglandular-hairy, otherwise sparsely to densely unicellular-hairy;

corolla usually bright pink, without blotch on upper lobe, funnelform, 25–45 mm, scattered, multicellular stipitate-glandular-hairy (hairs not forming distinct lines), otherwise sparsely to moderately unicellular-hairy on outer surface, petals connate, lobes 10–23 mm, tube gradually expanded into lobes, 11–27 mm (equaling or longer than lobes);

stamens 5, much exserted, ± unequal, 32–53 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 pedicel, 10–28 × 3–7 mm, stipitate-glandular-hairy, otherwise sparsely unicellular-hairy.

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 very sparsely to densely unicellular-hairy abaxially, especially near midvein, margins unicellular-ciliate.

2n

= 26.

Rhododendron prinophyllum

Ericaceae subfam. ericoideae

Phenology Flowering spring.
Habitat Acidic thickets or bogs, swampy to dry, rocky woods, bluffs, ravines, or along streams
Elevation 100-1500 m (300-4900 ft)
Distribution
from FNA
AL; AR; CT; IL; KY; MA; MD; MO; NC; NH; NJ; NY; OH; OK; PA; RI; TN; TX; VA; VT; WV
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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 prinophyllum is unusual in its strongly disjunct distribution. Plants in the western portion of the range often have longer corolla tubes and are most similar to R. canescens and R. periclymenoides, and can be distinguished from both by their broader, more gradually expanded corolla tubes and usually consistently glandular sepal margins, pedicels, and ovaries. Hybrids are known with R. calendulaceum and R. periclymenoides. The name R. roseum (Loiseleur) Rehder, which has been used for this species, is illegitimate because it was superfluous when published (K. A. Kron 1989).

(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. 469. 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. prunifolium, R. tomentosum, R. vaseyi, R. viscosum
Subordinate taxa
Synonyms Azalea prinophylla tribe Empetraceae
Name authority (Small) Millais: Rhododendrons, 229. 1917 , Link: Handbuch 1 602. (1829) — (as Ericeae)
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