Slag from the steel industry could help save some of Wales' most rare plants, according to an ecologist.
The material, regarded as waste, has been described as a potential "game-changer" when it comes to boosting biodiversity.
Barry Stewart, an ecologist from Swansea, has observed how slag heaps have self-seeded with plants which are on the edge of extinction in Wales.
He is now working with Carmarthenshire council to create a test bed where he hopes to grow some plants like wild liquorice, currently so rare it can only be found at two sites in the whole of Wales.
A slag heap is a hill or area of refuse from a mine or industrial site.
Mr Stewart has been recording plants for 30 years and gradually realised that wherever slag was present, wild flowers did well.
It was a site in Baglan, Neath Port Talbot, which led him to realise the value of slag.
At the right time of year the slag fields there are a mass of colour, he said, with plants which are on the edge of extinction in Wales.
"My university lecturer and I have spent many hours recording plants and saying this site is amazing, but not really paying too much thought as to what the material under the plants was," he said.
"But obviously the more we've studied it, we realised it's an amazing substance which supports this amazing assemblage of plants."
Mr Stewart said they had recorded more than 470 species at the site, including wild liquorice, Nottingham catchfly and various orchids.
"It's an ever-growing list," he said.