Rhododendron watsonii Hemsl. & Wils.

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Peter Norris, enabling the use of The Rhododendron Handbook 1998

Credits

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

Recommended citation
'Rhododendron watsonii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-watsonii/). Accessed 2024-09-15.

Genus

Rhododendron
Subsect. Grandia

Infraspecifics

R peregrinum

Other taxa in genus

Glossary

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.
ovary: Lowest part of the carpel containing the ovules; later developing into the fruit.
apex: (pl. apices) Tip. apical At the apex.
corolla: The inner whorl of the perianth. Composed of free or united petals often showy.
decurrent: Running down as when a leaf extends along a stem.
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).
midrib: midveinCentral and principal vein in a leaf.
oblanceolate: Inversely lanceolate; broadest towards apex.
ovary: Lowest part of the carpel containing the ovules; later developing into the fruit.
petiole: Leaf stalk.
style: Generally an elongated structure arising from the ovary bearing the stigma at its tip.

References

Royal Horticultural Society (1997). The Rhododendron Handbook 1998

Credits

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

Recommended citation
'Rhododendron watsonii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-watsonii/). Accessed 2024-09-15.

Foliage on Rhododendron watsonii. A plant on Mahee Island, Northern Ireland. June 2019. Image John Anderson.

Shrub or small tree, 2–6 m. Leaves 10–23 × 4.3–10 cm, obovate to oblanceolate, apex acute to acuminate, lower surface covered with a whitish thin compacted and agglutinated indumentum; petioles to 5 mm, stout and flattened. Flowers 12–15, in dense truss, c.7-lobed, white, with a crimson basal blotch, campanulate, nectar pouches lacking, 35–40 mm; stamens 14; ovary glabrous. Flowering March-April. Royal Horticultural Society (1997).

Distribution China Gansu, Sichuan

Habitat 2,600–3,300 m

RHS Hardiness Rating H4

Conservation status Near threatened (NT)

Taxonomic note A distinctive species on account of its short flattened petioles. It is allied to R. balangense. Royal Horticultural Society (1997)

An evergreen shrub or small tree, sometimes 30 ft high in the wild; young shoots stout, often 5⁄8 in. in diameter, scurfy white when young, becoming yellowish. Leaves oblanceolate to obovate, abruptly narrowed at the apex to a short point, tapered at the base to a thick, winged, yellowish stalk that is up to 1 in. long and 1⁄2 in. wide, 6 to 9 in. long, 2 to 4 in. wide, dark dull green and glabrous above, covered beneath with a pale, very close scurf; midrib broad and yellow above. Flowers produced from February to April in trusses of twelve to eighteen blooms and about 6 in. wide. Calyx small, 1⁄12 in. long, with even triangular teeth; flower-stalks 1 to 11⁄2 in. long, thinly downy. Corolla bell-shaped, 2 in. wide, nearly as deep, seven-lobed, white with a small purple blotch at the base. Stamens fourteen, shorter than the corolla, their white stalks downy towards the base. Ovary and style glabrous. (s. Grande)

Native of W. Szechwan; discovered by Wilson in 1904 and introduced by him. It is a little-known species, rare in cultivation, which is placed in the Grande series, of which it is an aberrant member, differing from all the other species, except R. peregrinum, in its glabrous ovary; the petiole is very short, with the decurrent base of the blade forming a wing on either side, as in R. praestans. During his second expedition for the Arnold Arboretum Wilson collected seed from trees 25 to 30 ft high, with trunks 2 to 21⁄2 ft in girth.

From the Supplement (Vol. V)

R. peregrinum, mentioned under this species on page 803, is probably a natural hybrid of R galactinum (Rev. 2, p. 431).

R peregrinum Tagg

Near to R. watsonii, but with the leaves rounded to subcordate at the base and the petiole up to 1 in. long. It occurred as a rogue among plants of R. galactinum raised by E. J. P. Magor of Lamellen, Cornwall, from Wilson’s 4254, collected in W. Szechwan on the Panlanshan, during his second expedition for the Arnold Arboretum.

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