Rhododendron periclymenoides

(Michaux) Shinners

Castanea 27: 95. 1962 ,.

Common names: Pinxterbloom azalea pinxter-flower election-pink
Endemic
Basionyms: Azalea periclymenoides Michaux Fl. Bor.-Amer. 1: 151. 1803
Treatment appears in FNA Volume 8. Treatment on page 468. Mentioned on page 458, 469, 470.

Shrubs, to 3 (–5) m, usually not rhizomatous. Stems: bark smooth to vertically furrowed, shredding; twigs scattered, multicellular eglandular-hairy (hairs unbranched) or such hairs ± absent, otherwise glabrous or sparsely unicellular-hairy. Leaves deciduous; petiole multicellular eglandular-hairy and unicellular-hairy; blade ovate to obovate, 3–9 (–12.5) × 1.4–3.8 (–5) cm, thin, membranous, margins entire, plane, ciliate, eglandular-hairy, often strikingly so, apex acute to obtuse, often mucronate, abaxial surface often glabrous or, sometimes, sparsely unicellular-hairy, sometimes sparsely eglandular-hairy, adaxial surface sometimes scattered eglandular-hairy, otherwise glabrous or, sometimes, sparsely unicellular-hairy. Floral bud-scales usually glabrous abaxially, margins unicellular-ciliate. Inflorescences 6–15-flowered; bracts similar to bud-scales. Pedicels 4–19 mm, eglandular-hairy, otherwise glabrous or sparsely unicellular-hairy. Flowers opening before or with leaves, erect to horizontal, slightly fragrant; calyx lobes 0.5–2.5 (–4) mm, surfaces and margins scattered, eglandular and/or, rarely, stipitate-glandular-hairy, otherwise glabrous or moderately unicellular-hairy; corolla deep pink to white with pink tube, without blotch on upper lobe, funnelform, 23–45 mm, scattered, multicellular eglandular-hairy and/or, less commonly, multicellular stipitate-glandular-hairy (hairs not forming distinct lines), otherwise sparsely to moderately unicellular-hairy on outer surface, petals connate, lobes 9–25 mm, tube usually gradually expanded into lobes, 12–27 mm (equaling or longer than lobes); stamens 5, much exserted, ± unequal, 32–68 mm. Capsules borne on erect pedicels, 10–30 × 3–6.5 mm, eglandular-hairy, otherwise glabrous or sparsely unicellular-hairy. Seeds without distinct tails; testa rather close, but ± loose. 2n = 26.


Phenology: Flowering spring.
Habitat: Mixed, dry to moist woods, often along streams, thickets, swamps
Elevation: 0-1000 m

Distribution

V8 916-distribution-map.gif

Ala., Conn., Del., Ga., Ky., Md., Mass., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va.

Discussion

Rhododendron periclymenoides is most similar to R. canescens, from which it can be distinguished by its less hairy leaves and bud scales, more gradually expanded corolla tube, and usually eglandular corolla indumentum; plants with stipitate-glandular hairs on the corolla occur sporadically throughout the range of this species (K. A. Kron 1993). Occasional hybridization with R. atlanticum, R. canescens, and R. prinophyllum probably occurs. The name R. nudiflorum Torrey has been incorrectly applied to this species; that name was superfluous when published and applies to R. luteum.

Selected References

None.

Lower Taxa

None.

eglandular-hairy +, unicellular-hairy +, , +  and glabrous +
unicellular-hairy +, , +, glabrous +  and eglandular-hairy +
Mucronate (?) +, Acute (?) +  and Obtuse (?) +
Walter S. Judd +  and Kathleen A. Kron +
(Michaux) Shinners +
smooth +  and vertically furrowed +
not flaky +
Azalea periclymenoides +
9 cm90 mm <br />0.09 m <br /> (12.5 cm125 mm <br />0.125 m <br />) +
3.8 cm38 mm <br />0.038 m <br /> (5 cm50 mm <br />0.05 m <br />) +
3 cm30 mm <br />0.03 m <br /> (9 cm90 mm <br />0.09 m <br />) +
ovate;obovate +
membranous +
thin;1.4cm;3.8cm +
scale-like +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
unicellular-hairy +, glabrous +  and eglandular-hairy +
0.3 cm3 mm <br />0.003 m <br /> (0.65 cm6.5 mm <br />0.0065 m <br />) +
Pinxterbloom azalea +, pinxter-flower +  and election-pink +
multicellular +
pink +  and white +
unicellular-hairy +, stipitate-glandular-hairy +  and eglandular-hairy +
rotate to crateriform campanulate cylindric globose or urceolate +
2.3 cm23 mm <br />0.023 m <br /> (4.5 cm45 mm <br />0.045 m <br />) +
Ala. +, Conn. +, Del. +, Ga. +, Ky. +, Md. +, Mass. +, N.J. +, N.Y. +, N.C. +, Ohio +, Pa. +, R.I. +, S.C. +, Tenn. +, Vt. +, Va. +  and W.Va. +
0-1000 m +
undifferentiated +
fusiform +
pendulous +  and erect +
usually ovoid;cylindric +
Mixed, dry to moist woods, often along streams, thickets, swamps +
multicellular +
unicellular-hairy +, glabrous +  and eglandular-hairy +
terminal +  and axillary +
deciduous +
fragrant +
9mm +  and 25mm +
unicellular-ciliate +  and ciliate +
unicellular-hairy +, glabrous +, stipitate-glandular-hairy +  and eglandular-hairy +
parietal +, axile +  and placentation +
tenuinucellate +  and unitegmic +
unicellular-hairy +, glabrous +  and eglandular-hairy +
0.4 cm4 mm <br />0.004 m <br /> (1.9 cm19 mm <br />0.019 m <br />) +
scale-like +
reduced +
not sticky +
multicellular +
unicellular-hairy +  and eglandular-hairy +
Flowering spring. +
4-5-carpellate +
distinct +
tailed +, flattened-ellipsoidal +  and fusiform +
unequal +
procumbent +  and prostrate +
creeping +  and sprawling +
peltate +  and capitate +
straight +
unicellular-hairy +, glabrous +  and stipitate-glandular-hairy +
Undefined tribe Empetraceae +
distinct +
Rhododendron periclymenoides +
Rhododendron +
species +
expanded +
1.2 cm12 mm <br />0.012 m <br /> (2.7 cm27 mm <br />0.027 m <br />) +
glabrous +  and hairy +
evergreen +, deciduous +  and perennial +
heterotrophic +, autotrophic +  and mycotrophic +