Rhododendron reticulatum G. Don

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

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'Rhododendron reticulatum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-reticulatum/). Accessed 2021-03-08.



  • R. rhomhkum Miq.


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.
A collection of preserved plant specimens; also the building in which such specimens are housed.
Taxonomic account of a single genus or family.
Lowest part of the carpel containing the ovules; later developing into the fruit.
Lacking hairs smooth. glabrescent Becoming hairless.
Bearing glands.
midveinCentral and principal vein in a leaf.
Lowest part of the carpel containing the ovules; later developing into the fruit.
Softly hairy.
Generally an elongated structure arising from the ovary bearing the stigma at its tip.


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

Recommended citation
'Rhododendron reticulatum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-reticulatum/). Accessed 2021-03-08.

Shrub or small tree, 1-8 m; young shoots soon glabrous. Leaves in whorls of up to three, at the ends of the branches, 3-6 x 1.5-4 cm, rhombic-ovate, apex acute, lower surface with short brown hairs, mainly on the midrib and veins; petioles covered with bristle-like hairs. Pedicels covered with adpressed brown hairs. Flowers 1-2(-3) per inflorescence, appearing before the leaves; calyx minute; corolla rose-purple (rarely white), funnel-campanulate, 25-30 mm; stamens 10; ovary villose, style glabrous. Flowering April-May. Royal Horticultural Society (1997)

Distribution  Japan S Honshu, Shikoku, Kyushu

Habitat 400-700 m

RHS Hardiness Rating H5

Awards FCC 1982 (Hydon Nurseries, Godalming) to a clone 'Sea King', raised from seed from Japan; corolla solitary, red-purple, with upper lobe slightly paler and sparingly spotted. AGM 1993

Conservation status Least concern (LC)

Taxonomic note R. reticulatum is allied to R. nudipes but differs in the pilose petioles and leaf midrib. Royal Horticultural Society (1997)

A deciduous azalea 5 to 8 ft high with stiff, erect, somewhat sparse branches, covered with a loose brownish wool when young. Leaves diamond-shaped, 1 to 212 in. long, 34 to 112 in. wide; dark dull green and very hairy above when young, becoming almost or quite glabrous by autumn; paler and very finely net-veined beneath; stalk 16 to 13 in. long, brown-woolly. Flowers solitary or in pairs (rarely twice as many). Calyx small, five-toothed, very hairy like the flower-stalk, which is about 14 in. long. Corolla purple, almost or quite unspotted, 112 to 2 in. across, lobes oblong, 12 in. wide, the three upper ones erect, the two smaller ones more deeply divided and pointed downwards. Stamens ten. Ovary densely coated with long white hairs (brown when dry); style glandular in the lower half. Bot. Mag., t. 6972. (s. Azalea ss. Schlippenbachii)

Native of Japan; described in 1834 from a young plant without flowers growing in Knight’s nursery, Chelsea. The original description is so incomplete that Don’s species was put on one side as incompletely known until Wilson resurrected it in the Monograph of Azaleas (1921). Until then it had been known by Miquel’s name R. rhombicum. The Knight introduction was probably lost, but the species was reintroduced to Europe around 1865 and reached Britain soon after. It is quite a pretty species, bearing its showy flowers before the leaves unfold, but the colouring inclines to magenta-purple as a rule and clashes badly with reds and near-blues. It is perfectly hardy.

R. reticulatum is a somewhat variable species in the wild, and several of its forms have been given specific rank by Japanese botanists (see R.Y.B. 1948, pp. 114-16, and Ohwi’s Flora of Japan (1965), pp. 700-2). The description given above is of the form commonly cultivated in this country; all the garden specimens in the Kew Herbarium belong to it, including the original of the plate in the Botanical Magazine. This form, easily recognised in the flowering stage by the ten stamens, densely hairy ovary and the style glandular in the lower half, agrees well with the form given specific rank by Makino as R. wadanum. It is comparatively low-growing, seldom more than 8 ft high.

From the Supplement (Vol. V)

† cv. ‘Sea King. – An excellent selection with rosy lilac flowers, which was awarded a First Class Certificate in 1982. It was raised at the Hydon Nursery from seeds collected in Japan by Dr Rokuju.

R dilatatum Miq.

R. reticulatum f. pentandrum Wils

Leaves soon glabrous on both surfaces, hence distinguishable from the common form of R. reticulatum even when out of flower. Stamens five only. Ovary glandular, not hairy; style glabrous. Bot. Mag., t. 7681. Native of Japan; introduced by Messrs Veitch in 1883. Although it is very similar to R. reticulatum (wadanum) in general appearance, the distinctive characters given above appear to be well correlated and together make it more than just a five-stamened form of that species. It has the same garden value.