Rhododendron macrophyllum |
Rhododendron minus |
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big leaf rhododendron, California rhododendron, California rose bay, coast rhododendron, Pacific rhododendron, western rhododendron |
Piedmont rhododendron |
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Habit | Shrubs or trees, to 5 m, sometimes rhizomatous. | Shrubs, to 3(–5) mm, often rhizomatous. | ||||
Stems | bark smooth to vertically furrowed, shredding; twigs with basally branched, crisped/matted, eglandular hairs, very quickly glabrate. |
bark smooth to vertically furrowed, shredding; twigs with ferrugineous, multicellular, broad-rimmed, glandular-peltate scales. |
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Leaves | persistent; petiole glabrous; blade elliptic to slightly ovate or obovate, (6–)8.5–14(–20) × 2.5–5.5(–7.5) cm, thick, coriaceous, margins entire, plane to revolute, glabrous, apex acute to obtuse or slightly acuminate, surfaces scattered eglandular-hairy (hairs branched basally, crisped, very quickly deciduous), abaxial surface ± smooth. |
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). |
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Inflorescences | 10–20-flowered; bracts similar to bud scales. |
5–10-flowered; bracts similar to bud scales. |
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Pedicels | 30–60 mm, glabrous. |
5–15 mm, with ferruginous scales. |
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Flowers | opening after development of leaves (of flowering shoots), erect to horizontal, fragrant; calyx lobes 1–1.5 mm, glabrous, except margins eglandular- and stipitate-glandular-hairy; corolla white to pink or rose-purple, with yellowish green spots on upper lobe, broadly campanulate, 24–48 mm, outer surface glabrous, petals connate, lobes 14–30 mm, tube gradually expanding into lobes, 10–23 mm; stamens 10, included, ± unequal, 16–37 mm. |
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. |
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Capsules | borne on erect pedicels, 13–25 × 4–7 mm, eglandular-hairy (hairs ferruginous, branched or unbranched) and, often, stipitate-glandular-hairy. |
borne on erect pedicels, 6–14 × 2.9–5 mm, with ferruginous, peltate scales. |
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Seeds | without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, loose. |
with short, blunt/truncate tails at each end; testa closely appressed. |
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Floral | bud scales multicellular eglandular-hairy (hairs branched basally), and unicellular-hairy (hairs short to elongate) abaxially, margins eglandular-hairy (hairs branched). |
bud scales ferruginous-lepidote, sometimes also unicellular-hairy abaxially, margins unicellular-ciliate. |
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2n | = 26. |
= 26. |
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Rhododendron macrophyllum |
Rhododendron minus |
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Phenology | Flowering spring–summer. | |||||
Habitat | Forest and forest margins, thickets | |||||
Elevation | 50-1600 m [160-5200 ft] | |||||
Distribution |
CA; OR; WA; BC
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AL; FL; GA; NC; SC; TN
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Discussion | Rhododendron macrophyllum, R. maximum, and R. catawbiense represent subg. Hymenanthes (Blume) K. Koch in North America; the subgenus is represented by hundreds of species in temperate eastern Asia and is characterized by its branched, eglandular hairs (D. F. Chamberlain 1982). These showy plants are frequently used as ornamentals. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 8, p. 462. | FNA vol. 8, p. 460. | ||||
Parent taxa | ||||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | R. californicum | |||||
Name authority | D. Don ex G. Don: Gen. Hist. 3: 843. 1834 , | Michaux: J. Hist. Nat. 1: 412. 1792 , | ||||
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