"Rhododendron ferrugineum (sometimes called alpenrose, snow-rose, or rusty-leaved alpenrose) is an evergreen shrub that grows just above the tree line in the Alps, Pyrenees, Jura and ...
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northern Apennines, on acid soils. It is the type species for the genus Rhododendron. It may grow up to 1 m tall and produces clusters of pinkish-red, bell-shaped flowers throughout the summer. The undersides of the leaves are covered in rust-brown spots, which give the species the second part of its binomial name (ferrugineum, Latin for ´rust-coloured, ferruginous´). This is in contrast to Rhododendron hirsutum, which has no such brown colouring, has hairy edges to the leaves and grows over limestone. Where the two species co-occur (usually on soils of intermediate pH), the hybrid Rhododendron × intermedium may occur; as its name suggests, it is intermediate in form between the two parental species." - (en.wikipedia.org 17.12.2019)