Rhododendron keiskei Miq.

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

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'Rhododendron keiskei' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-keiskei/). Accessed 2020-10-29.

Genus

Infraspecifics

Other species in genus

Glossary

acute
Sharply pointed.
apex
(pl. apices) Tip. apical At the apex.
article
(in Casuarinaceae) Portion of branchlet between each whorl of leaves.
calyx
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
corolla
The inner whorl of the perianth. Composed of free or united petals often showy.
glabrous
Lacking hairs smooth. glabrescent Becoming hairless.
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
lanceolate
Lance-shaped; broadest in middle tapering to point.
midrib
midveinCentral and principal vein in a leaf.
obtuse
Blunt.

References

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Credits

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

Recommended citation
'Rhododendron keiskei' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-keiskei/). Accessed 2020-10-29.

Small shrub, (0.1-)0.3-3 m; young shoots scaly, sometimes also puberulent. Leaves (2.5-)3.5-7.5 x (0.8-)1.1-2.8 cm, lanceolate to narrowly elliptic, apex acute or acuminate, upper surface with midrib puberulent, also hairy towards base of lamina, lower surface with large distant brown scales. Flowers 2-3(-4), in a loose terminal inflorescence; calyx with lobes absent or to 2.5 mm, frequently ciliate; corolla pale yellow, unspotted, zygomorphic, funnel-campanulate, 18-24 mm, outer surface scaly, somtimes also puberulent; stamens 10; ovary scaly, impressed below the declinate, glabrous style. Flowering April-May. Royal Horticultural Society (1997)

Distribution  Japan

Habitat 600-1,850 m

RHS Hardiness Rating H5

Conservation status Least concern (LC)

An evergreen shrub 6 ft high in the wild; young branches slightly scaly. Leaves 112 to 212 in. long, 34 to 114 in. wide, oval-oblong, pointed at the apex, rounded or tapered at the base, more or less scaly on both surfaces, but especially beneath; stalk about 14 in. long. Flowers pale, rather dull yellow, 114 to 2 in. across, in clusters of about four or five; corolla broadly bell-shaped; calyx undulated into five very shallow lobes; stamens ten, slightly downy; flower-stalk scaly, 12 to 34 in. long. Blossoms in April and May. Bot. Mag., t. 8300. (s. and ss. Triflorum)

Native of Japan from the main island southward as far as Yakushima; introduced in 1908 and quite hardy. It is a rather variable species, both in habit and in the size and shape of its leaves. In his collection at The Grange, Benenden, Kent, Capt. Collingwood Ingram has a tall-growing plant which he considers to be a good match for typical R. keiskei, in which the leaves are lanceolate, acute, up to 3 in. long and 34 in. wide, and the petioles bristly when young. The commonly cultivated form, by contrast, is of low-growing habit and has shorter and relatively broader leaves, which are obtuse or subacute at the apex, with a stout midrib and glabrous petioles. Ingram considers the latter to represent a distinct species, which he has named R. laticostum (R.C.Y.B. 1971, pp. 28-30). These two cultivated forms are certainly very distinct, but the difference would probably be much less clear-cut if a wide range of wild specimens were examined. In the same article, Ingram published a second species, R. trichocalyx, described from a cultivated plant. He informs us that he is now satisfied that the plant in question is a hybrid of garden origin.


var. keiskei

Shrub, 1-2m; leaves 3-9 x 1.1-2.8cm; flowers yellow.

Awards AM 1929 (H. White, Windlesham); flowers pale yellow.


var. ozawae T.Yamaz

Dwarf shrubs, 10-15cm tall; leaves 1.5-2.5 x 1-1.5cm; flowers yellow.

Awards AM 1970 (B.N. Starling, Epping Upland, Essex) to a clone of var. ozawae, ‘Yaku Fairy’; habit very dwarf, flowers yellow. AGM 1993, to a clone of var. ozawae, ‘Yaku Fairy’.

The dwarf forms of this distinctive species, especially those of var. ozawae from Yakushima, are good rock garden subjects.


'Yaku Fairy'

A prostrate plant with flowers about 1{3/4} in. across in trusses of two to five. Leaves lanceolate, up to 1{1/2} in. long. Award of Merit April 14, 1970, when shown by Barry N. Starling. It was collected on Mt Kuromi, Yakushima (see R.C.Y.B. 1971, pp. 104-6).

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