Rhododendron yakushimanum • Yakushima rhododendron

Rhododendron • シャクナゲ • 石楠花 • shakunage

The plants growing along the service road are not listed alphabetically in the Plant Book, but in order of appearing south to north, which makes them much easier to identify that the rest of the plants in Garden; the E side of the road is marked as the Area ZZE, and the W side as Area ZZW.  It is on the east side of service road, close to south end of the garden where one can find Rhododendron yakushimanum:

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SJG • 5/24/12 – Rhododendron yakushimanum • Yakushima rhododendron, Area ZZE

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SJG • 5/24/12 – Rhododendron yakushimanum • Yakushima rhododendron, Area ZZE; corolla pink, fades to white

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SJG • 5/24/12 – Rhododendron yakushimanum • Yakushima rhododendron, Area ZZE; suede-like brown coating on the underside of the leaves (called ‘indumentum’ – a covering of fine hairs)

Here a link to interesting write-up from a Quarterly Bulletin of  American Rhododendron SocietyRhododendron yakushimanum, known outside Japan for just 50 years, was quickly accepted as one of the most beautiful rhododendrons in the world, and its popularity becomes ever greater. This species is found wild only on Yakushima, an island about 26 kilometers (16 miles) in diameter, located 60 kilometers out in the ocean from the south tip of Japan. […]

Its basic features are widely known and can be summarized as follows: habit of growth may be upright but is often dense and compact, giving the plants a domed shape prized by many growers; leaves are dark green, shining, often curled down, usually with thick, woolly indumentum on the lower surface; flowers are always campanulate, i.e., bell-shaped, opening from pink buds, then becoming lighter, usually almost pure white in full bloom, but with notable color variation to be seen in the wild. Trusses may be large and dense, of nice shape, or may be loose and broad, the latter kind sometimes covering almost all the plant. […]

Kathy L.  commented:
‘Also, the term for the soft, velvet-like brown underside of the Yakushimanum is ‘indumentum’. – soft hairy covering.’

From wikipedia on the subject of indumentum:  An indumentum is a covering of fine hairs or bristles (rarely scales) on a plant[1] or insect. In plants, the indumentum types are:
pubescent
hirsute
pilose
villous
tomentose
stellate
scabrous
scurfy

The use of an indumentum on plants can be pollen-related to propagate the plant or simply protective, or even decorative due to mutations. The use of an indumentum on insects can also be pollen-related, as on bees, sensory like whiskers, or for varied other uses including adhesion and poison. […]

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