Rhododendron maximum |
Rhododendron canadense |
|
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great laurel, great rosebay, rhododendron, rosebay, rosebay rhododendron |
Canada rosebay, rhodora |
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Habit | Shrubs or trees, to 10 m, sometimes rhizomatous. | Shrubs, to 1 m, rhizomatous. |
Stems | bark smooth to vertically furrowed, shredding; twigs multicellular stipitate-glandular-hairy and eglandular-hairy (hairs basally branched, crisped/matted), glabrate in age. |
bark ± smooth to slightly shredding; twigs sparsely multicellular eglandular- and shorter stipitate-glandular-hairy (hairs unbranched), also unicellular-hairy. |
Leaves | persistent; petiole multicellular-hairy (hairs ± branched), often glabrescent; blade oblong to obovate or elliptic, (6–)9–20(–31) × (1.5–)2–5(–8) cm (length/width ratio 2.4–8), thick, coriaceous, margins entire, revolute to ± plane, glabrous or sparsely hairy (hairs branched), apex acuminate to sometimes acute, surfaces scattered stipitate-glandular-hairy and eglandular-hairy (hairs forming dense mat, basally branched, crisped, abaxially becoming sticky and matted, forming ± scaly or continuous, pale, shellaclike coating, smooth to slightly roughened, hairs ± deciduous adaxially). |
deciduous; petiole multicellular eglandular- and stipitate-glandular-hairy and unicellular-hairy; blade elliptic to oblong or obovate, 1–8.3 × 0.4–3 cm, thin, membranous to chartaceous, margins entire, usually ± revolute, sometimes plane, eglandular- and unicellular-hairy, apex acute to rounded, abaxial surface eglandular- and stipitate-glandular-hairy, also unicellular-hairy, (± glaucous), adaxial surface scattered eglandular- and stipitate-glandular-hairy, also unicellular-hairy. |
Inflorescences | 10–25-flowered; bracts similar to bud scales. |
sometimes fasciculate, 3–9-flowered; bracts similar to bud scales. |
Pedicels | 17–60 mm, multicellular stipitate-glandular-hairy. |
3–10 mm, (usually glaucous), usually sparsely stipitate-glandular-hairy, and sometimes also densely unicellular-hairy. |
Flowers | opening after development of leaves (of flowering shoots), erect to horizontal, not or only slightly fragrant; calyx lobes 2–6 mm, stipitate-glandular-hairy; corolla white to pink, rarely deep pink to purple, with yellowish green spots on upper lobe, campanulate, 20–36 mm, scattered stipitate-glandular-hairy on outer surface, petals connate, lobes 10–23 mm, tube gradually expanding into lobes, 7–16 mm; stamens 10, included, ± unequal, 14–26 mm; (ovary stipitate-glandular-hairy). |
appearing before or, sometimes, with leaves, erect to horizontal, fragrant; calyx lobes 0.4–1.5 mm, often scattered stipitate-glandular-hairy, sometimes also unicellular-hairy, margins glandular- and/or eglandular-ciliate; corolla rose-purple to pink, rarely white, unspotted or red-spotted on upper 3 lobes, irregularly shaped, clearly 2-lipped due to very extensive connation of 3 upper lobes contrasting with 2 elongate, widely divergent lower lobes, 12–22 mm, glabrous or, sometimes, sparsely stipitate-glandular-hairy on outer surface, petals connate, upper lobe 3–8 mm, lateral lobes 12–22 mm (closely connate with upper lobe), lower lobes 12–22 mm, tube absent due to deep division between 2 lower lobes and between lateral and lower lobes; stamens 10, exserted, ± unequal, 9–20 mm. |
Capsules | borne on erect pedicels, 8–20 × 4–6.5 mm, stipitate-glandular-hairy. |
borne on erect pedicels, 0.7–1.7 × 0.3–0.6 mm, multicellular stipitate-glandular- and eglandular-hairy and densely unicellular-hairy. |
Seeds | without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, loose. |
with flattened tails; testa tightly appressed. |
Floral | bud scales stipitate-glandular-hairy, eglandular-hairy (hairs ferruginous, crisped), and short unicellular-hairy abaxially, margins hairy (hairs branched, long-celled). |
bud scales unicellular-hairy abaxially, and often stipitate-glandular- and eglandular-hairy, margins unicellular-hairy. |
2n | = 26. |
= 52. |
Rhododendron maximum |
Rhododendron canadense |
|
Phenology | Flowering summer. | Flowering spring. |
Habitat | Stream banks, mesic woods | Moist to dry, coniferous or mixed conifer-deciduous forests, thickets, open rocky areas, lake margins, bogs, swamps |
Elevation | 0-1900 m (0-6200 ft) | 0-1900 m (0-6200 ft) |
Distribution |
AL; CT; GA; KY; MA; MD; ME; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WV
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CT; MA; ME; NH; NJ; NY; PA; RI; VT; NB; NF; NS; ON; PE; QC
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Discussion | Individuals of Rhododendron maximum are beautiful, cold-hardy shrubs and are frequently cultivated as ornamentals. Hybrids with R. catawbiense occur. This species has been attributed in standard floras to eastern Canada but not confirmed there by specimens. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Rhododendron canadense is distinctive and is most closely related to R. vaseyi; together they constitute sect. Rhodora (Linnaeus) G. Don (W. S. Judd and K. A. Kron 1995). Rhododendron canadense is sometimes cultivated for its showy flowers. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 8, p. 463. | FNA vol. 8, p. 464. |
Parent taxa | Ericaceae > subfam. Ericoideae > Rhododendron | Ericaceae > subfam. Ericoideae > Rhododendron |
Sibling taxa | ||
Synonyms | R. ashleyi | Rhodora canadensis |
Name authority | Linnaeus: Sp. Pl. 1: 392. 1753 , | (Linnaeus) Torrey: in New York State, Rep. Geol. Surv., 151. 1841 , |
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