Rhododendron maximum

Linnaeus

Sp. Pl. 1: 392. 1753 ,.

Common names: Rosebay great laurel
IllustratedEndemic
Synonyms: Rhododendron ashleyi Coker
Treatment appears in FNA Volume 8. Treatment on page 463. Mentioned on page 456, 462.

Shrubs or trees, to 10 m, sometimes rhizomatous. Stems: bark smooth to vertically furrowed, shredding; twigs multicellular stipitate-glandular-hairy and eglandular-hairy (hairs basally branched, crisped/matted), glabrate in age. 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). Floral bud-scales stipitate-glandular-hairy, eglandular-hairy (hairs ferruginous, crisped), and short unicellular-hairy abaxially, margins hairy (hairs branched, long-celled). Inflorescences 10–25-flowered; bracts similar to bud-scales. Pedicels 17–60 mm, multicellular stipitate-glandular-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). Capsules borne on erect pedicels, 8–20 × 4–6.5 mm, stipitate-glandular-hairy. Seeds without distinct tails, flattened portion of testa well developed at each end; testa expanded, dorsiventrally flattened, loose. 2n = 26.


Phenology: Flowering summer.
Habitat: Stream banks, mesic woods
Elevation: 0-1900 m

Distribution

V8 905-distribution-map.gif

Ala., Conn., Ga., Ky., Maine, Md., Mass., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va.

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.

Selected References

None.

Lower Taxa

None.

... more about "Rhododendron maximum"
Walter S. Judd +  and Kathleen A. Kron +
Linnaeus +
smooth +  and vertically furrowed +
not flaky +
20 cm200 mm <br />0.2 m <br /> (31 cm310 mm <br />0.31 m <br />) +
5 cm50 mm <br />0.05 m <br /> (8 cm80 mm <br />0.08 m <br />) +
9 cm90 mm <br />0.09 m <br /> (20 cm200 mm <br />0.2 m <br />) +
oblong;obovate or elliptic +
coriaceous +
thick;2cm;5cm +
scale-like +
stipitate-glandular-hairy +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (2 cm20 mm <br />0.02 m <br />) +
stipitate-glandular-hairy +
0.4 cm4 mm <br />0.004 m <br /> (0.65 cm6.5 mm <br />0.0065 m <br />) +
Rosebay +  and great laurel +
white +  and pink rarely deep pink +
stipitate-glandular-hairy +
rotate to crateriform campanulate cylindric globose or urceolate +
2 cm20 mm <br />0.02 m <br /> (3.6 cm36 mm <br />0.036 m <br />) +
Ala. +, Conn. +, Ga. +, Ky. +, Maine +, Md. +, Mass. +, N.H. +, N.J. +, N.Y. +, N.C. +, Ohio +, Pa. +, R.I. +, S.C. +, Tenn. +, Vt. +, Va. +  and W.Va. +
0-1900 m +
undifferentiated +
fusiform +
unicellular-hairy +, eglandular-hairy +  and stipitate-glandular-hairy +
erect;horizontal +
fragrant +
pendulous +  and erect +
usually ovoid;cylindric +
Stream banks, mesic woods +
multicellular +
terminal +  and axillary +
persistent +
10mm +  and 23mm +
hairy +  and glabrous +
revolute;more or less plane +
parietal +, axile +  and placentation +
tenuinucellate +  and unitegmic +
multicellular +
stipitate-glandular-hairy +
1.7 cm17 mm <br />0.017 m <br /> (6 cm60 mm <br />0.06 m <br />) +
scale-like +
reduced +
not sticky +
glabrescent +  and multicellular-hairy +
Flowering summer. +
4-5-carpellate +
distinct +
tailed +, flattened-ellipsoidal +  and fusiform +
Illustrated +  and Endemic +
yellowish green +
unequal +
procumbent +  and prostrate +
creeping +  and sprawling +
peltate +  and capitate +
straight +
eglandular-hairy +  and stipitate-glandular-hairy +
Rhododendron ashleyi +
distinct +
Rhododendron maximum +
Rhododendron +
species +
flattened +
expanded +
expanding +
0.7 cm7 mm <br />0.007 m <br /> (1.6 cm16 mm <br />0.016 m <br />) +
multicellular +
glabrate +, eglandular-hairy +  and stipitate-glandular-hairy +
evergreen +, deciduous +  and perennial +
tree +  and shrub +
heterotrophic +, autotrophic +  and mycotrophic +