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'Rhododendron tsusiophyllum' from the website Trees and Shrubs Online (treesandshrubsonline.
Bean treated this species under the monotypic genus Tusiophyllum, as T. tanakae. We reproduce below Bean’s description unamended, together with that from the Rhododendron Book. The text below that is derived from Bean but expanded and heavily adapted reflect the current taxonomic situation.
Dwarf shrub, to c.0.3 m; young shoots covered with adpressed flattened bristles. Leaves of one kind, 1–1.2 × 0.5–0.7 cm, obovate, apex acute, upper surface glabrous when mature, lower surface with a few bristles on the midrib, otherwise glabrous; petioles covered with bristles. Pedicels apparently hairy. Flowers 1–4 per inflorescence; calyx minute; corolla pink in bud, fading to white, tubular-campanulate, c.10 mm; stamens (4–)5; ovary covered with bristles, style glabrous. Flowering July. Royal Horticultural Society 1997.
A spreading semi-evergreen shrub to about 11⁄2 ft high, its short, whorled branchlets clad with appressed bristly hairs. Leaves ovate to lanceolate or oblanceolate, up to 3⁄4 in. long and 1⁄4 in. or slightly more wide, clustered at the ends of the branchlets, appressed-hairy on both sides, more so above. Flowers white, shortly stalked, borne in June in terminal umbellate clusters or sometimes solitary; bud-scales brown and papery. Calyx very small. Corolla tubular, about 3⁄8 in. long, and about 1⁄4 in. wide across the spreading five-lobed limb, downy on the outside, silky-hairy within. Stamens five, included. Fruit a capsule, resembling that of a rhododendron but with three-chambers only. Bean 1981
Distribution Japan S Honshu and adjacent Islands
Habitat c. 500 m
RHS Hardiness Rating H4
Conservation status Least concern (LC)
A distinctive species on account of its tubular-campanulate corolla with short lobes, half as long as tube. Royal Horticultural Society (1997)
Native of Japan, confined to a few localities in Honshu; described by Maximowicz shortly after its discovery and assigned its own genus Tsusiophyllum. The name was chosen because the appressed strigose hairs on the leaves recalled those in Rhododendron sect. Tsusia Planch ex Maxim (series Azalea subseries Obtusum), though the plant was not at that time thought closely related. It is now placed in subg. Tsutsusi sect. Tsutsusi, within which it forms a clade with R. indicum, R. tschonoskii and R. serpyllifolium (Kron & Powell 2009). This species is unusual within the genus for its three-celled ovary (which, together with the hairy outer surface of the corolla, usefully distinguishes it from the ‘menziesias’) and for its anthers that open by slits instead of pores (Bean 1981).
Introduced by Wilson in 1915. It is hardy and needs the same conditions as other ericaceous shrublets, but is one of the least interesting of these. It received an Award of Merit in 1965. Propagated by cuttings.