Peak ponticum Posted on June 4, 2019

Few species have been as demonized as Rhododendron ponticum. Among foresters it is a hissing and a byword; among conservations not much better. The charge sheet: it self-sows with prodigious energy and success in typical forest land, which is often acid and rained-on. The seedlings then grow with villainous vigour and smother other seedlings and saplings. They create a damp shade, which is no bad thing in many woods, until it falls under a new suspicion: of harbouring and encouraging Phytophthera ramorum, or P. kernowiae, pathogens responsible for the death of among other things, larches…

For years there were grants available for the thanklessly repetitive tasks of spraying, or better injecting it with herbicide. The grants systems change but the problem remains. Foresters still shudder at the sight of mauve blooms in the woods in May, however pretty they may be. Tourists crowd buses to visit the hotspots. There is no denying the spectacle of hillsides aglow with it. Nothing shows up the shades of purple more vividly than the old slate-mines of North Wales, where whole mountainsides are slate-black and ponticum purple.


I am schizophrenic about it. Last week in Snowdonia no one could deny its beauty. It can form phalanxes of flowers by the roadside or peep from high among forest trees where flowers are the last thing you expect to see. Its shades of purple, or mauve, sometimes intense, sometimes much paler, are always a startling contrast with woodland green. Yet the sight of it among our trees, often flowering (as weeds often do) when a mere stripling, two or three years old, makes me shudder. There is no alternative to costly destruction.

One botanist has been convinced by its supernatural vigour to declare it a new species, and baptised it R. x superponticum. Other authorities say that’s rubbish. Although it may possibly have swapped a few genes with other species, such are the American R. catawbiense, it remains true to the R. ponticum standard – or rather one of them: the strictly pontic one is from northern Turkey, the other (oddly enough) from Portugal. They are apparently not physically different enough to be two species, but the one that spreads is consistently the Iberian strain. So ‘super’ is fair enough for its performance but doesn’t make it a distinct species.

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