Rhododendron occidentale |
Rhododendron austrinum |
|
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California azalea, western azalea |
Florida azalea, orange azalea |
|
Habit | Shrubs or trees, to 8(–10) m, usually not rhizomatous. | Shrubs or trees, to 3(–5) m, usually not rhizomatous. |
Stems | bark smooth to vertically furrowed, shredding; twigs sparsely to densely multicellular stipitate-glandular-hairy or unicellular-hairy, or glabrous, sometimes only unicellular-hairy. |
bark smooth to vertically furrowed, shredding; twigs conspicuously multicellular stipitate-glandular-hairy, otherwise ± moderately to densely unicellular-hairy. |
Leaves | 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. |
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. |
Inflorescences | 3–15-flowered; bracts similar to bud scales. |
9–24-flowered; bracts similar to bud scales. |
Pedicels | 9–26 mm, stipitate-glandular- and, sometimes, also eglandular-hairy. |
5–17 mm, stipitate-glandular-hairy, otherwise ± densely unicellular-hairy. |
Flowers | 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. |
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. |
Capsules | 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). |
borne on erect pedicels, 14–26 × 3–5.5 mm, sparsely to densely stipitate-glandular-hairy, otherwise moderately to densely unicellular-hairy. |
Seeds | without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, ± loose. |
without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, ± loose. |
Floral | 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. |
bud scales densely to moderately unicellular-hairy abaxially, margins unicellular-ciliate, also partly glandular-serrate. |
2n | = 26. |
= 26. |
Rhododendron occidentale |
Rhododendron austrinum |
|
Phenology | Flowering spring–summer. | Flowering spring. |
Habitat | Moist, wooded slopes and canyon bottoms, along streams, thickets, bogs, serpentine ridges, ocean bluffs | Wooded slopes, bluffs or lowlands along streams |
Elevation | 0-2700 m (0-8900 ft) | 0-100 m (0-300 ft) |
Distribution |
CA; OR
|
AL; FL; GA; MS
|
Discussion | The flowers of Rhododendron occidentale show an exceptional range of variation in color. (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.) |
Source | FNA vol. 8, p. 467. | FNA vol. 8, p. 466. |
Parent taxa | Ericaceae > subfam. Ericoideae > Rhododendron | Ericaceae > subfam. Ericoideae > Rhododendron |
Sibling taxa | ||
Synonyms | Azalea occidentalis, Azalea californica, R. occidentale var. paludosum, R. sonomense | Azalea austrina |
Name authority | (Torrey & A. Gray) A. Gray: in W. H. Brewer et al., Bot. California 1: 458. 1876 , | (Small) Rehder: in L. H. Bailey, Stand. Cycl. Hort. 6: 3571. 1917 , |
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