Rhododendron minus |
Rhododendron austrinum |
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Piedmont rhododendron |
Florida azalea, orange azalea |
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Habit | Shrubs, to 3(–5) mm, often rhizomatous. | Shrubs or trees, to 3(–5) m, usually not rhizomatous. | ||||
Stems | bark smooth to vertically furrowed, shredding; twigs with ferrugineous, multicellular, broad-rimmed, glandular-peltate scales. |
bark smooth to vertically furrowed, shredding; twigs conspicuously multicellular stipitate-glandular-hairy, otherwise ± moderately to densely unicellular-hairy. |
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Leaves | persistent; petiole with ferruginous, broad-rimmed, glandular-peltate scales and unicellular-hairy; blade narrowly elliptic to elliptic or oval, sometimes obovate, (1–)5–8(–13) × (1–)2–3.5(–5.5) cm, thick, coriaceous, margins entire, plane to conspicuously revolute, with scattered, glandular-peltate scales, apex acute or acuminate or obtuse to rounded, surfaces with scattered, ferruginous, broad-rimmed, glandular-peltate scales abaxially, (scales ± deciduous adaxially). |
deciduous; petiole multicellular stipitate-glandular-hairy and unicellular-hairy; blade ovate to obovate, 3–11 × 1.5–4.5 cm, thin, membranous, margins entire, plane, ciliate, eglandular- and stipitate-glandular-hairy, apex acute to obtuse, often mucronate, abaxial surface ± moderately unicellular-hairy, adaxial surface sparsely scattered stipitate-glandular-hairy, otherwise ± moderately unicellular-hairy, rarely glabrescent. |
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Inflorescences | 5–10-flowered; bracts similar to bud scales. |
9–24-flowered; bracts similar to bud scales. |
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Pedicels | 5–15 mm, with ferruginous scales. |
5–17 mm, stipitate-glandular-hairy, otherwise ± densely unicellular-hairy. |
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Flowers | opening before or after development of leaves, erect to horizontal, fragrant; calyx lobes 0.5–2 mm, with ferruginous scales; corolla dark to very pale pink or white, upper lobe usually with greenish spots, campanulate to funnelform, 15–37 mm, with scattered, ferruginous, peltate scales on outer surface, petals connate (for 3/4+ their lengths), lobes 8–19 mm, tube gradually expanding into lobes, 8–22 mm; stamens 10, included to slightly exserted, ± unequal, 13–26 mm. |
opening before or with leaves, erect to horizontal, slightly or not fragrant; calyx lobes 0.5–2.5 mm, scattered stipitate-glandular-hairy, otherwise unicellular-hairy, margins long stipitate-glandular-hairy; corolla yellow to orange, with usually red or orange-red tube, with indistinct, darker yellow, orange, or red blotch on upper lobe, funnelform, 25–45 mm, scattered stipitate-glandular-hairy, otherwise ± moderately unicellular-hairy on outer surface, petals connate, lobes 9–20 mm, tube ± gradually expanded into lobes, 15–25 mm (longer than lobes); stamens 5, much exserted, ± unequal, 52–77 mm. |
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Capsules | borne on erect pedicels, 6–14 × 2.9–5 mm, with ferruginous, peltate scales. |
borne on erect pedicels, 14–26 × 3–5.5 mm, sparsely to densely stipitate-glandular-hairy, otherwise moderately to densely unicellular-hairy. |
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Seeds | with short, blunt/truncate tails at each end; testa closely appressed. |
without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, ± loose. |
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Floral | bud scales ferruginous-lepidote, sometimes also unicellular-hairy abaxially, margins unicellular-ciliate. |
bud scales densely to moderately unicellular-hairy abaxially, margins unicellular-ciliate, also partly glandular-serrate. |
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2n | = 26. |
= 26. |
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Rhododendron minus |
Rhododendron austrinum |
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Phenology | Flowering spring. | |||||
Habitat | Wooded slopes, bluffs or lowlands along streams | |||||
Elevation | 0-100 m (0-300 ft) | |||||
Distribution |
AL; FL; GA; NC; SC; TN
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AL; FL; GA; MS
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Discussion | Varieties 2 (2 in the flora). Rhododendron minus is here circumscribed broadly, including R. carolinianum and R. chapmanii, and the latter is considered to be a distinct variety (W. H. Duncan and T. M. Pullen 1962). Variety chapmanii is federally listed. This species is often grown as an ornamental. Rhododendron minus and R. lapponicum are members of subg. Rhododendron, as indicated by their glandular-peltate scales; the subgenus is represented by hundreds of species in eastern and southern Asia (see J. Cullen 1980). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Rhododendron austrinum is most closely related to R. luteum Sweet of eastern Europe, Turkey, and the Caucasus region and to R. occidentale (K. A. Kron 1993). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 8, p. 460. | FNA vol. 8, p. 466. | ||||
Parent taxa | Ericaceae > subfam. Ericoideae > Rhododendron | Ericaceae > subfam. Ericoideae > Rhododendron | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Azalea austrina | |||||
Name authority | Michaux: J. Hist. Nat. 1: 412. 1792 , | (Small) Rehder: in L. H. Bailey, Stand. Cycl. Hort. 6: 3571. 1917 , | ||||
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