The rhododendron

The rhododendron is an emblematic melliferous plant and ranks among the most important nectar sources in mountain regions. In Switzerland, two species are present: Rhododendron ferrugineum, which grows on acidic soils, and Rhododendron hirsutum, which prefers calcareous soils.

In Valais, the former species is widespread throughout the region, whereas the latter occurs only on the right bank of the Rhône. They grow at altitudes between 1400 and 2500 m. Their abundant flowering dominates the subalpine landscape, illuminating pastures with purplish-pink hues.

Belonging to the Ericaceae family, Rhododendron ferrugineum and the ciliate (or hirsute) rhododendron are shrubs with strongly branched, downward-arching woody stems that form a dense, virtually impenetrable plant layer. The leaves are evergreen, elongated, and leathery; those of Rhododendron ferrugineum show rust-colored spots on the underside, whereas the leaves of the hirsute rhododendron are green on both sides and have hairy margins, which explains their respective names.

The inflorescences bear around ten flowers, grouped into short, dense umbels. The corolla is formed by five petals fused at the base, creating a kind of tube at the bottom of which lies the nectary, a gland specialized in nectar secretion, through which bees enter in search of this valuable resource.

Although honey flow largely depends on climatic conditions, rhododendron nectar can produce a monofloral honey even in Switzerland, in the relevant Alpine cantons, notably Ticino, Grisons, and Valais. This rare honey is very light in its liquid state and almost white when solid; its flavor is mild, fruity, and subtly woody; its crystallization is slow and very fine. It contains numerous trace elements, which give it high value.

Rhododendron honey is therefore recommended in apitherapy for patients undergoing chemotherapy, as it is thought to significantly reduce the side effects of cancer treatments.

By contrast, other rhododendron species growing in Asia Minor produce a honey that is toxic to humans: Xenophon, the Greek writer, philosopher, and statesman of the 4th century BC, recounts the story of an army decimated after consuming this honey.

Sources

T. Silberfeld, C. Reeb, Les plantes mellifères, 2016

Various authors, Giardinaggio senza problemi, Guida completa del Reader’s Digest, 1981

Various authors, Le traité Rustica de l’apiculture, 2002

Miels monofloraux suisses, Alp Forum 2005, No. 23f (reissue 2008)