Many of the special plants here are ‘northern’ species at the southern edge of their range.  However we also have ‘southern’ species at the northern edge of their range.  This unusual combination of northern and southern species growing together occurs nowhere else in Britain.  This ‘Teesdale Assemblage’ of rare plants is considered to have survived continuously since shortly after the last glaciation some 10-12,000 years ago.

As well as the famous Spring gentian, rare plants you may know include Yellow Saxifrage, Alpine Rush, Bird’s-eye Primrose, Dwarf Milkwort, Teesdale Violet, Rare Spring-sedge and Hoary Rock-rose.

Two of the most important places for rare plants are Widdybank Fell and Cronkley Fell.  A special type of rock, ‘sugar limestone’, reaches the surface on these two fells and nowhere else in Britain.  Dry grassland and wet flushed habitats on the sugar limsetone support several of the rare species.  Other habitats in Teesdale which are particularly good for the special plants include the Tees riverbank, the cliffs and the high fell tops.

The Teesdale Assemblage is often considered to include just over 20 rare plant species.  Our project however includes a wider list of roughly 100 species which are of conservation interest.