Rhododendron prunifolium

(Small) Millais

Rhododendrons, 230. 1917 ,.

Common names: Plumleaf azalea
EndemicConservation concern
Basionyms: Azalea prunifolia Small Fl. SE. U.S. ed. 2, 1356, 1375. 1913
Treatment appears in FNA Volume 8. Treatment on page 470. Mentioned on page 457, 466.

Shrubs or trees, to 5 (–6) m, usually not rhizomatous. Stems: bark smooth to vertically furrowed, shredding; twigs glabrous. Leaves deciduous; petiole usually multicellular eglandular-hairy and unicellular-hairy; blade ovate to obovate, 3–11 (–15.2) × 1–4 (–5) cm, thin, membranous to chartaceous, margins entire, plane, ciliate, eglandular-hairy, apex acute to obtuse, often mucronate, abaxial surface glabrous, adaxial surface glabrous or, rarely, sparsely scattered eglandular-hairy. Floral bud-scales glabrous abaxially, margins unicellular-ciliate. Inflorescences 4–7-flowered; bracts similar to bud-scales. Pedicels 5–12 mm, eglandular-hairy. Flowers opening after development of leaves, erect to horizontal, not fragrant; calyx lobes 1–3 (–4) mm, glabrous or sparsely unicellular-hairy, margins eglandular-hairy; corolla red to orange-red or orange, with indistinct darker blotch on upper lobe, funnelform, 36–53 mm, glabrous or very sparsely long stipitate-glandular-hairy, sometimes also sparsely unicellular-hairy on outer surface, petals connate, lobes 11–22 mm, tube abruptly expanded into lobes, 23–35 mm (± equaling or much longer than lobes); stamens 5, much exserted, ± unequal, 64–84 mm. Capsules borne on erect pedicels, 15–22 × 4.5–7 mm, densely, stiffly eglandular-hairy and sparsely unicellular-hairy. Seeds without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, ± loose. 2n = 26.


Phenology: Flowering summer.
Habitat: Shady forests, especially ravines along streams
Elevation: 30-200 m

Discussion

Of conservation concern.

Rhododendron prunifolium is most closely related to R. flammeum, R. cumberlandense, and R. calendulaceum, and can be distinguished from all of those orange- to red-flowered species by its nearly glabrous and more gradually expanded corolla tube and by the indistinct nature of the floral blotch (K. A. Kron 1993). This species is federally protected.

Selected References

None.

Lower Taxa

None.

... more about "Rhododendron prunifolium"
eglandular-hairy +, , +  and glabrous +
Mucronate (?) +, Acute (?) +  and Obtuse (?) +
Walter S. Judd +  and Kathleen A. Kron +
(Small) Millais +
smooth +  and vertically furrowed +
not flaky +
Azalea prunifolia +
11 cm110 mm <br />0.11 m <br /> (15.2 cm152 mm <br />0.152 m <br />) +
4 cm40 mm <br />0.04 m <br /> (5 cm50 mm <br />0.05 m <br />) +
3 cm30 mm <br />0.03 m <br /> (11 cm110 mm <br />0.11 m <br />) +
ovate;obovate +
membranous;chartaceous +
thin;1cm;4cm +
scale-like +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
unicellular-hairy +  and glabrous +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
1.5 cm15 mm <br />0.015 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
unicellular-hairy +  and eglandular-hairy +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
Plumleaf azalea +
red +  and orange-red or orange +
unicellular-hairy +, stipitate-glandular-hairy +  and glabrous +
rotate to crateriform campanulate cylindric globose or urceolate +
3.6 cm36 mm <br />0.036 m <br /> (5.3 cm53 mm <br />0.053 m <br />) +
Ala. +  and Ga. +
30-200 m +
undifferentiated +
fusiform +
erect;horizontal +
not fragrant +
pendulous +  and erect +
usually ovoid;cylindric +
Shady forests, especially ravines along streams +
multicellular +
terminal +  and axillary +
deciduous +
11mm +  and 22mm +
unicellular-ciliate +  and ciliate +
eglandular-hairy +
parietal +, axile +  and placentation +
tenuinucellate +  and unitegmic +
eglandular-hairy +
0.5 cm5 mm <br />0.005 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
scale-like +
reduced +
not sticky +
multicellular +
unicellular-hairy +  and eglandular-hairy +
Flowering summer. +
4-5-carpellate +
Rhododendrons, +
distinct +
tailed +, flattened-ellipsoidal +  and fusiform +
Endemic +  and Conservation concern +
unequal +
procumbent +  and prostrate +
creeping +  and sprawling +
peltate +  and capitate +
straight +
Undefined tribe Empetraceae +
distinct +
Rhododendron prunifolium +
Rhododendron +
species +
flattened +
expanded +
expanded +
2.3 cm23 mm <br />0.023 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
evergreen +, deciduous +  and perennial +
tree +  and shrub +
heterotrophic +, autotrophic +  and mycotrophic +