JARS v46n2 - Subsection Glauca
Reprinted from the Seattle Chapter January 1991 newsletter
Most of the rhododendrons in this subsection (series) are remarkably similar in foliage and growth habit. To the average rhododendron lover the only significant difference is in the flowers. The general characteristics of the plants in this group are: 10 inches to 6 feet in height, smooth mahogany-colored peeling bark, leaves white or grayish underneath, aromatic and generally varying in shape and size.
The flowers are 2 to 10 in the truss, varying in color from pink to purple, sometimes yellow or white. Only two members of this group bear yellow flowers: R. brachyanthum which flowers in late May or early June and R. luteiflorum which flowers in early April. R. brachyanthum can always be distinguished from any other species by the length (1 to 2 inches) of the flower pedicel. Also its leaves, when crushed, are the most aromatic of any rhododendron.
R. glaucophyllum with its pink to reddish-purple flowers will reach an ultimate height of four feet and, if grown in full sun, will be a very attractive densely mounded shrub. There is also an albino form.
R. charitopes bears apple-blossom pink flowers dotted with crimson. Some forms will have flowers of rose to rose-crimson without spots. A very attractive shrub for a sunny location. It tends to be somewhat scraggly in the shade.
R. pruniflorum with crimson, plum-purple or lavender-purple flowers is so similar to R. tsangpoense that it requires careful scanning of the leaf undersurface to tell them apart. Both plants are typical Glauca shrubs with a compact habit and aromatic leaves and deserve a special place in the garden.
R. tubiforme is considered by Davidian to be a distinct species but classified by Cullen as a variation of R. glaucophyllum. More upright and taller growing (up to 7 feet) than the other plants in the subsection, it is readily distinguished from R. glaucophyllum by its tubular corolla and its long, straight style. All the other rhododendrons in this group have a deflexed (bent) style.