A RARE plant found only in parts of the Highlands and Islands has disappeared from 75 spots where it once thrived, experts have found.
But 19 new populations have also been found of the Scottish primrose, Primula scotica, which is regarded by botanists as one of the most scarce and attractive plants in the world.
Scottish Natural Heritage is now to conduct new research to map its distribution.
Primula scotica is found only in Caithness, Sutherland and Orkney.
The most recent survey showed it was present at 194 places along the coast between Durness in north-west Sutherland and Dunbeath in north-east Caithness – 110 places in Sutherland and 84 in Caithness.
Research showed it appeared to be thriving best in areas where traditional crofting grazing methods continued. These included Strathy Point and Faraid Head, near Durness, and Holborn Head, near Thurso. In Orkney common sites included Yesnaby, the west coasts of Rousay and Westray, Papay, North Hill and South Walls.
The 75 spots in Caithness and Sutherland where it has been lost are as a result of over-long grass due to lack of grazing.
This happens particularly where fences have been erected which exclude sheep and cattle. Other causes of losses included agricultural improvement, tree planting and house building.
The survey said: "Where conditions are suitable Primula scotica grows by the thousand in parts of Caithness and Sutherland. However, in other places where it was previously discovered finding just one was a challenge."
The distinctive plant has a flower on average 8mm in diameter with five heart-shaped petals and a bright yellow centre. In Orkney it inspired a local jeweller to make a collection in silver, enamels and gold.
Sally Ward, the SNH officer in Golspie who managed the survey, said: "This tiny plant grows mainly in short grassland close to the sea, often near the top of dramatic cliffs.
"Sometimes it's a walk to see it, but all the more memorable because, as well as the flower itself, you can see some of our most lovely coasts.
"Primula scotica is best appreciated with one's face close to the ground so that you can achieve an excellent view of the flower with its pink petals and yellow centre.
"The key to its success – or failure – is grazing in which grass is kept tightly cropped. The fortunes of Primula scotica rise and fall with livestock numbers and as it is so small – less than 5cm high – it cannot compete against long grass which shades it out."
The current survey is the latest in a series of surveys of Primula scotica carried out since the 1960s. All locations at which the plant was found growing previously were visited, as well as new places with suitable habitat.