Rhododendron semibarbatum Maxim.

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

Recommended citation
'Rhododendron semibarbatum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-semibarbatum/). Accessed 2024-05-28.


Other taxa in genus


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.
Immature shoot protected by scales that develops into leaves and/or flowers.
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
Occurring in two forms.
Lacking hairs smooth. glabrescent Becoming hairless.
Bearing glands.
globularSpherical or globe-shaped.
Flower-bearing part of a plant; arrangement of flowers on the floral axis.
midveinCentral and principal vein in a leaf.
Egg-shaped; broadest towards the stem.
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 semibarbatum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-semibarbatum/). Accessed 2024-05-28.

Deciduous shrub, to 2(–3) m; young shoots puberulous and with gland-tipped hairs, leaves turning wine-red in autumn, clustered at the end of short-growing branches, 2–6 × 1–2.6 cm, elliptic or ovate, apex apiculate to obtuse, base rounded or cuneate, margin serrulate and sometimes ciliate, lower surface glabrous except for the puberulous midrib and ciliate veins. Flowers borne laterally, below the vegetative buds, solitary; calyx c.2 mm, lobes rounded; corolla white, with a pink flush and rose-purple flecks, rotate, with a short wide tube and spreading lobes, c.20 mm across; stamens 5, strongly dimorphic; ovary setose and densely glandular, style glabrous. Flowering June. Royal Horticultural Society (1997)

Distribution  Japan Honshu, Shikoku, Kyushu

Habitat Mountains

RHS Hardiness Rating H5

Conservation status Least concern (LC)

Taxonomic note A distinctive species on account of its strongly dimorphic stamens. The arrangement of the one-flowered inflorescence is similar to that of Subgen. Azaleastrum but it is very diffeent in other characters. Royal Horticultural Society (1997)

A deciduous shrub 2 to 8 ft high with downy and hairy, glandular young shoots. Leaves oval to ovate, very variable in size from 34 to 2 in. long, 38 to 1 in. wide, bluntish at the apex, rounded or nearly so at the base, minutely toothed on the margins and slightly bristly on the midrib and veins beneath; stalk up to 38 in long, downy and bristly. Flowers solitary, produced from lateral buds near the ends of the branchlets (the terminal bud is a growth-bud); pedicels 18 in. or slightly more long, glandular and bristly, like the short calyx. Corolla rotate with a short tube and five rounded, spreading lobes, white or yellowish white, freely dotted with red at the base, about 34 in. across. Stamens five, very unequal, the three lower ones glabrous or nearly so, the other two much shorter and nearly covered with brisdes. Ovary globose, bristly in the upper part; style glabrous. Bot. Mag., t. 9147. (s. Semibarbatum)

Native of central and southern Japan; described by Maximowicz from a specimen collected by Tschonoski; it was introduced by him to St Petersburg, but did not reach Britain until Wilson sent seeds in 1914, which were distributed by the Arnold Arboretum. As a garden plant it has little to recommend it, but it is of considerable botanical interest as a member of the Azaleastrum group (see p. 588).