Rhododendron maximum L.

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Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Rhododendron maximum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-maximum/). Accessed 2024-05-25.



  • Rhododendron procerum Salisb.


Other taxa in genus


(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
The inner whorl of the perianth. Composed of free or united petals often showy.
Lowest part of the carpel containing the ovules; later developing into the fruit.
(pl. apices) Tip. apical At the apex.
Lacking hairs smooth. glabrescent Becoming hairless.
Bearing glands.
A covering of hairs or scales.
Egg-shaped; broadest towards the stem.
Folded backwards.
Generally an elongated structure arising from the ovary bearing the stigma at its tip.


Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Rhododendron maximum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-maximum/). Accessed 2024-05-25.

Shrub or small tree, 1.3–3.5 m; young shoots tomentose and stalked-glandular though soon glabrescent; bud scales deciduous. Leaves 10–16 × 3–5 cm, oblanceolate to elliptic, upper surface glabrous, lower surface with a thin fugaceous indumentum that is embedded in a surface film that usually persists towards the leaf base, especially near the midrib; petioles usually sparsely tomentose, even when mature. Flowers 14–25, in a dense truss; calyx 3–5 mm; corolla white to rose-purple, with yellowish green flecks, campanulate, nectar pouches lacking, 25–30 mm; ovary pilose and stalked-glandular, style glabrous. Flowering July. Royal Horticultural Society (1997)

Distribution  CanadaUnited States E

Habitat 300–1,700 m

RHS Hardiness Rating H7

Awards AM 1974 (Crown Estate Commissioners, Windsor) to a clone 'Summertime'; flowers white, suffused at tip with shades of red-purple, throat with yellow-green spots.

Conservation status Least concern (LC)

Taxonomic note Closely allied to R. macrophyllum but with narrower leaves, 3.3–4× as long as broad. Royal Horticultural Society (1997)

An evergreen shrub or, in the wild, sometimes a tree over 30 ft high, with a short trunk 1 ft in diameter; young wood reddish and scurfy; outer flowerbud scales leaf-like, the inner ones reflexed at the apex. Leaves narrowly obovate to oblong, 4 to 10 in. long, 1 to 212 in. wide, cuneate at the base, dark green above, pale beneath, and covered there with a close, thin indumentum which usually disappears within a few months but sometimes persists for more than a year; stalk stout, 12 to 1 in. long. Flowers up to thirty in a compact terminal truss on viscid and downy stalks 1 to 112 in. long. Calyx with ovate, rounded lobes, slightly downy, 316 in. long. Corolla wide campanulate, rose-coloured or purplish pink, spotted with greenish yellow or deep yellow-orange on the upper lobes, about 112 in. across, with five rounded lobes. Stamens eight to twelve, the filaments downy. Ovary glandular-hairy; style glabrous. Bot. Mag., t. 951.

(s. and ss. Ponticum)

Native of the eastern USA; introduced to Britain in 1736 by Peter Collinson, but now rarely seen in gardens. Its trusses are small and are produced late, at the end of June and in July, and make little display among the young growths, which by that time are almost fully expanded. It has, however, played its part in the development of the hardy hybrids (see further on pages 818–19).

f. album (Pursh) Fern.

R. maximum var, album Pursh
R. purshii G. Don

Flowers white; wild with the type.