Rhododendron minus |
Rhododendron occidentale |
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Piedmont rhododendron |
California azalea, western azalea |
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Habit | Shrubs, to 3(–5) mm, often rhizomatous. | Shrubs or trees, to 8(–10) 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 sparsely to densely multicellular stipitate-glandular-hairy or unicellular-hairy, or glabrous, sometimes only 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 eglandular- or stipitate-glandular-hairy and unicellular-hairy; blade ovate or obovate to elliptic, (2.5–)3.5–8.2(–10.8) × 1.2–2.9(–3.6) cm, thin, membranous, margins entire, plane, ciliate, eglandular-hairy, sometimes also stipitate-glandular-hairy, apex acute to obtuse, often mucronate, abaxial surface glabrous or sparsely unicellular-hairy, often also stipitate-glandular-hairy (or, rarely, stipitate-glandular- and eglandular-hairy), adaxial surface sparsely scattered, multicellular eglandular- and/or stipitate-glandular-hairy and unicellular-hairy, or glabrous. |
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Inflorescences | 5–10-flowered; bracts similar to bud scales. |
3–15-flowered; bracts similar to bud scales. |
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Pedicels | 5–15 mm, with ferruginous scales. |
9–26 mm, stipitate-glandular- and, sometimes, also eglandular-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 with leaves or after they have expanded, erect to horizontal, fragrant or mephitic-scented; calyx lobes 1–4(–9) mm, often stipitate-glandular- and/or eglandular-hairy, sometimes also unicellular-hairy, margins usually stipitate-glandular-hairy; corolla white with contrasting yellow blotch on upper lobe, white and pink or salmon, or pink with orange blotch on upper lobe, rarely white with yellow lines at throat, or with tube white to red, funnelform, 30–58 mm, stipitate-glandular-hairy and, rarely, also eglandular-hairy, otherwise sparsely to moderately unicellular-hairy or these hairs absent on outer surface, petals connate, lobes 13–29 mm, tube gradually expanding into lobes, 15–29 mm (equaling or longer than lobes); stamens 5, much exserted, ± unequal, 40–75 mm. |
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Capsules | borne on erect pedicels, 6–14 × 2.9–5 mm, with ferruginous, peltate scales. |
borne on erect pedicels, 12–22 × 4–14 mm, multicellular stipitate-glandular-hairy, sometimes also eglandular-hairy, otherwise sparsely unicellular-hairy (unicellular hairs rarely absent). |
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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 sparsely to densely unicellular-hairy abaxially, rarely also sparsely eglandular- or stipitate-glandular-hairy, margins unicellular-ciliate, or with glands and cilia mixed, or glandular. |
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2n | = 26. |
= 26. |
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Rhododendron minus |
Rhododendron occidentale |
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Phenology | Flowering spring–summer. | |||||
Habitat | Moist, wooded slopes and canyon bottoms, along streams, thickets, bogs, serpentine ridges, ocean bluffs | |||||
Elevation | 0-2700 m (0-8900 ft) | |||||
Distribution |
AL; FL; GA; NC; SC; TN
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CA; OR
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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.) |
The flowers of Rhododendron occidentale show an exceptional range of variation in color. (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. 467. | ||||
Parent taxa | Ericaceae > subfam. Ericoideae > Rhododendron | Ericaceae > subfam. Ericoideae > Rhododendron | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Azalea occidentalis, Azalea californica, R. occidentale var. paludosum, R. sonomense | |||||
Name authority | Michaux: J. Hist. Nat. 1: 412. 1792 , | (Torrey & A. Gray) A. Gray: in W. H. Brewer et al., Bot. California 1: 458. 1876 , | ||||
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