Rhododendron tomentosum |
Rhododendron maximum |
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Labrador tea, marsh Labrador tea, northern Labrador tea, trappers tea |
great laurel, great rosebay, rhododendron, rosebay, rosebay rhododendron |
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Habit | Shrubs, to 0.5 m, rhizomatous. | Shrubs or trees, to 10 m, sometimes rhizomatous. |
Stems | creeping or prostrate; bark ± smooth; twigs unicellular-hairy and with flattened, glandular scales, scales often obscured by dense, ferruginous, long-crisped, multicellular hairs. |
bark smooth to vertically furrowed, shredding; twigs multicellular stipitate-glandular-hairy and eglandular-hairy (hairs basally branched, crisped/matted), glabrate in age. |
Leaves | persistent, (fragrant when crushed); petiole with unicellular and/or peltate scales and, sometimes, ferruginous, long-crisped hairs; blade ± linear, 2–5 × 1–4 cm (often much longer than wide), coriaceous, margins entire, revolute, glabrous, apex acute, abaxial surface with sparse to dense, glandular-peltate scales without broad rim, scales often obscured by dense (to sparse), ferruginous, long-crisped, multicellular hairs sometimes forming dense, ± uniform mat, adaxial surface rugose with scattered, lepidote scales and sometimes also with white, unicellular hairs along impressed midrib, midrib usually lanate. |
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). |
Inflorescences | slightly rounded, 10–35-flowered; bracts lepidote abaxially, margins ciliate, long-crisped-hairy, sometimes also unicellular-hairy. |
10–25-flowered; bracts similar to bud scales. |
Pedicels | 5–26 mm, sparsely eglandular-hairy (hairs ferruginous, elongated), with ferruginous, long-crisped, unicellular and/or peltate scales, sometimes also long-stalked, multicellular glandular-hairy. |
17–60 mm, multicellular stipitate-glandular-hairy. |
Flowers | radially symmetric, opening after leaves (of flowering shoots), ± erect, not fragrant; calyx lobes ca. 1 mm, outer surface densely to sparsely unicellular-hairy (hairs tan), and multicellular, stipitate-glandular-hairy (hairs red) on margins; corolla white to cream, without blotch, ± rotate, 2–8 mm, inner surface often densely unicellular-hairy, petals appearing distinct or only slightly connate basally, lobes 5–7 mm; stamens 10, exserted, ± equal, 4.4–8.5 mm. |
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). |
Capsules | borne on apex of sharply recurved pedicels, 2.5–5 × 1–3 mm (only slightly longer than wide), with sparse to dense, lepidote scales, acropetally dehiscent. |
borne on erect pedicels, 8–20 × 4–6.5 mm, stipitate-glandular-hairy. |
Seeds | somewhat elongated beyond narrow ends; testa closely appressed. |
without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, loose. |
Floral | bud scales with lepidote scales and unicellular-hairy abaxially, margins unicellular-hairy. |
bud scales stipitate-glandular-hairy, eglandular-hairy (hairs ferruginous, crisped), and short unicellular-hairy abaxially, margins hairy (hairs branched, long-celled). |
2n | = 26, 52. |
= 26. |
Rhododendron tomentosum |
Rhododendron maximum |
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Phenology | Flowering spring–summer. | Flowering summer. |
Habitat | Bogs, muskeg, tundra, raised beach ridges | Stream banks, mesic woods |
Elevation | 0-1800 m (0-5900 ft) | 0-1900 m (0-6200 ft) |
Distribution |
AK; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland; Europe; Asia
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AL; CT; GA; KY; MA; MD; ME; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WV
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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.) |
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Source | FNA vol. 8, p. 459. | FNA vol. 8, p. 463. |
Parent taxa | Ericaceae > subfam. Ericoideae > Rhododendron | Ericaceae > subfam. Ericoideae > Rhododendron |
Sibling taxa | ||
Synonyms | Ledum palustre, Ledum decumbens, Ledum palustre subsp. decumbens, R. subarcticum, R. tolmachevii, R. tomentosum subsp. decumbens, R. tomentosum var. subarcticum | R. ashleyi |
Name authority | Harmaja: Ann. Bot. Fenn. 27: 204. (1990) | Linnaeus: Sp. Pl. 1: 392. 1753 , |
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