You will probably never see this plant in SJG, because it is well hidden behind the green hedge surrounding the Tea House garden in Area W, and even if you are inside the roji you can’t see it – it grows to the left/north of the oribe lantern, but behind and below big pieris japonica.
Even with tips on how to find it, it took me some time and going off the stepping stone path and behind bushes where you will never be allowed to go… It has quite interesting bell-shaped purplish-pink flowers and oval vivid-green leaves that emerge in clusters of about 5, similar to r. quinquefolium, except that menziesia leaves are thicker and more fleshy.
From Rainy Side Gardeners: Menziesia ciliicalyx var. multiflora; Family: Ericaceae. Origin: Japan. […] The genus Menziesia is named after naturalist Archibald Menzies (1754-1842), who explored our Pacific coast with Captain Vancouver from 1791 to 1795. Seven species in this genus are endemic to eastern North America and Japan. A slow-growing shrub, M. ciliicalyx var. multiflora does best in a woodland setting, in partial shade; however, it will grow in full sun in the Northwest. Related to the rhododendron, and like one, this rounded shrub prefers our acidic soils. It shrub adapts well to growing in a container, provided the soil medium drains well. […] Their photo shows purplish/pink flowers similar to ours.
This entry, form UK Alpine Garden Society, disputes the flower color: Erect habit, rarely more than 60cm high, often less, but up to 1m. in the wild. Leaves obovate to ovate-oblong, 2.5-5cm in length, loosely pilose and ciliate when young, membranous, glaucous beneath. Flowers narrowly bell-shaped, pale yellow or greenish-yellow, 1.3-1.7cm long, in umbels of three to eight, late spring to early summer. Japan, Honshu only, on hills and mountains in scrub. M.c. var. multiflora (syn. M. multiflora) has a racemose inflorescence and small flowers with short often glabrous, calyx lobes. Often treated as a distinct species. Honshu, Hokkaido, Shikoku. M.c. var. purpurea (syn. M. multiflora var. purpurea, M. lasiophylla) bears rose-purple flowers and has the leaves coarsely longpilose above (hairless in forma glabrescens). Honshu only. In British gardens, var. purpurea sometimes masquerades as the true M. purpurea, a shrub to 2m. or more with rose-pink, purplish or white flushed pink flowers. There are also several dwarf, slow-growing clones typified by ‘Buchanan’s Dwarf.
From the website Japanese Tree Flowers (Japan):
Scientific name: Menziesia multiflora Maximovicz
Synonyms: Menziesia ciliicalyx Maximovicz var. multiflora (Maximovicz) Makino; Menziesia multiflora Maximovicz var. purpurea (Makino) Ohwi; Menziesia multiflora Maximovicz var. tsuchiyae Hiyama; Menziesia multiflora Maximovicz var. tsuchiyae Hiyama forma glabrifolia Sugimoto
Common name: (Japanese common name) urajiro-youraku [youraku like folower with bacside white leaves (youraku = an ornamental goods of Buddha)], azuma-turigane-tutuji [Azuma bells tutuji (Azuma = an old name of Northeastern Japan, tutuji = Rhododendron plants)]
(English common name) none
Distribution: (Japan) Hokkaido (Southwestrn region), Honshu (west of Centrak region), Shikoku
(Other nations) none
Reference: Menziesia ciliicalyx Maxim. var. multiflora (Maxim.) Makino
Note: Menziesia multiflora Maximovicz is not a synonym of Menziesia ciliicalyx Maximovicz. […]
Check the pics on the Japanese and British websites – maybe we have menziesia var. purpurea, or perhaps our menziesia masquerades as another one, I will probably never know; also note that the good professor Summer in Japan doesn’t list menziesia as endemic to North America, only to Japan.