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Species In Our Midst
Rhododendron micranthum

by Elizabeth Carlhian

Rhododendron micranthum
Picture by S & J Perkins
Rhododendron micranthum growing in Salem, NH

Rhododendron micranthum

This surprising little shrub is in Section Rhododendron, Subsection Micrantha, the scaly rhododendrons. This is a monotypic subsection containing only this one species; its closest ally is probably Subsection Lapponica, from which it differs in its winged seeds, which suggest a relationship with Maddenia or Boothia

The specific epithet means "small flowered" from the Greek. In Chinese it is rather poetically known as "shining mountain white" or "white mirror." R. micranthum was first described by Turczaninov in 1837 from a specimen collected on the mountains north of Bejing. Wilson introduced R. micranthum in 1901 from Hubei. It was illustrated in the "Botanical Magazine" in 1908.

R. micranthum is widely distributed; it grows wild from North Korea through central and northern China and Manchuria in thickets and scrub on cliffs and dry gorges and on ridges, at elevations from 1500-2500 m (5000-8000 ft).

Reports on its hardiness vary. Greer says -5°F, but David Leach lists it as -25°F, or H1. People in the Concord, MA area say it is quite hardy.

R. micranthum forms a bushy evergreen shrub, 4 to 5 feet tall, looking more like a Spirea or Ledum (now a rhododendron) in growth habit. The leaves are oblong-elliptic, less than 1" long and very narrow. They are glabrous above and densely scaly and light brown below. The branches are slender and graceful. The flowers are white, unspotted, and tiny. The corolla is funnel campanulate and about 1/3 inch across. The inflorescence may contain as many as 20 flowers. The rachis (central stalk of the flower cluster) is long, unlike most other lepidotes. Although the flower buds become quite large by the previous autumn, the plant does not flower until June or July after most rhododendrons.

I can find no record of any success in hybridizing R. micranthum, not surprising given its lack of any near relatives.

For a plant with so many positive qualities -- hardiness, good form, number of flowers, late time of bloom -- it is surprising that this species is so little seen in our collections. Because there is quite a good deal of variation among the cultivars of R. micranthum, it would seem to be a plant ready to be worked with to make superior forms available for our gardens.

Elizabeth Carlhian, Concord, MA

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