Scottish Rare Plant Project at Royal Botanic Garden

Woolly Willow, Salix lanata, at the Royal Botanic Garden in Edinburgh
Woolly Willow, Salix lanata, at the Royal Botanic Garden in Edinburgh

Thursday, May 22, started cold, wet, and foggy with an east wind, when we left Berwickshire to travel to Edinburgh for the Scottish Wildlife Trust’s second summer meeting this year.

Eight members met our host, Dr Heather McHaffee, and as luck would have it the rain stopped as she took us into a private section of the Botanics to see the plants which are cultivated in the Scottish Rare Plant Project.

There are several aims in this project which is principally to collect most of the 170 threatened native plants in Scotland and propagate them in the Botanic Garden, with the intention of returning the resulting progeny to their native habitats to enhance the wild populations, also to save seeds of those plants and maintain then in a long term seed bank and, to gain experience of growing the plants in cultivation so that a reserve can be held in the garden and at other sites.

On the Island of Arran are three species of Rowan which are found nowhere else in the entire world, all are critically endangered and one of them, Sorbus pseudomeiniachii has been reduced from three plants to one in recent years through natural erosion at its only site.

Only 10 seeds were found from which one has germinated and grown away. Vegetative propagation of Sorbus is tricky but they have been successful with chip budding and to everyone’s surprise a few cuttings have rooted. The task of building up stocks is under way and the intention is to return new, young plants, back to protected sites on Arran.

There are a number of mountain willows which have small, isolated populations which are vulnerable to natural disasters and overgrazing by Red Deer. One of those is the Woolly Willow, Salix lanata, which is only found at 14 sites. This willow has separate male and female plants and if individuals are scattered far apart there is little opportunity for viable seeds to be produced. Luckily it is easy to root from cuttings, which have been collected from more or less all the individual plants in some populations, bulked up and returned to the sites where they originated. To keep them out of reach of grazing deer in places they have been planted on rock ledges and cliffs and climbers from Glen More Lodge abseiled down from above and under instruction planted young plants on safe ledges.

The Whorled Solomon’s-seal, Polygonatum verticillatum, is restricted to 10 small sites. At a site in Glen Tilt rhizomes were collected under licence just before the colony was washed away, new plantings with the original stock were made in 2007 and 2010 in Glen Tilt at safe locations.

The Sticky Catchfly, Silene viscaria, was reduced to a few individuals through grazing by rabbits and encroaching gorse in Holyrood Park. Seeds have been collected and are held in the long term seed bank and young plants planted on ledges which are difficult for Rabbits to reach and the Gorse is being cut back.