Scleranthus perennis ssp perennis Perennial Knawel RRR DD N Endemic
There are quite a few claims for the title of Britain's rarest plant including Diapensia lapponica (Diapensia) and Artemisia norvegica (Norwegian Mugwort) known from only two locations on the tops of remote mountains in northern Scotland or perhaps Cypripedium calciolus (Lady's-slipper Orchid) which was down to a single plant but has since been cloned. You could propose the Ghost Orchid (Epipogium aphyllum) which haunts many a botanist as it has been seen since only once since 1986 (by 2011).
Scleranthus perennis ssp perennis must be in the top ten as it lives on a few square centimetres of its single known site on exposed, ancient Dolerite rock with its roots in nor more than a few centimetres of soil. It could be eliminated from the World's flora by a single accidental kick of a climbing boot from a curious but unaccompanied botanist. In some years it doesn't grow and in others rabbits graze the few shoots which do appear. In more recent years it has been endangered by passing visitors who like a rocky habitat for their prawn sandwich consumption. The very rare mosses which also live nearby are equally at risk from extinction by picnic.
It re-appears after blank years only because of the seed bank buried in these few cubic centimetres of soil in Mid Wales. Scleranthus perennis ssp perennis is supposed to be the erect form of Perennial Knawel with larger flowers than its more "abundant" cousin Scleranthus perennis ssp prostatus in East Anglia and I suppose you can see the shoots tending to point upwards. The flowers have no petals. What you see in the photos are sepals (usually five) with five to ten stamens and two styles (Stace).
In spite of its precarious existence, visitors can be taken to see it it as long as they don't mind climbing on rock via an almost non existent path. It isn't very high up but it is very exposed with nothing to hold on to so don't bother if you have a problem with heights. Contact Andrew Ferguson or Sue Buckingham at the Countryside Council for Wales.
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| Scleranthus perennis ssp perennis Perennial Knawel |
Stanner Rocks, Mid Wales, 11th May 2007
Added on 12th May 2007, updated 26th May 2008, updated 7th September 2011, updated 1st February 2012