Thieves have stolen five "extremely rare" Serbian trees from woodland near Perth.
Forest Enterprise Scotland (FES) said the picea omorika trees had no commercial value, but were a "priceless component" of a conservation project.
Genetic material from the trees was being used in an international programme to conserve conifers.
The thieves took the trees from Kinnoull Woodland Park last week. Police Scotland are investigating.
FES said the trees were part of Perth and Kinross Countryside Trust's work with the Royal Botanic Garden Edinburgh to help conserve conifer species at risk of extinction in their native habitat.
The trust's Tom Christian said: "The climate and landscape of Perthshire are ideal for growing conifers and the area provides a very important safe haven for rare and endangered species from around the world.
"Each Conifer Conservation Programme tree is grown from seed that has been specially collected from its native habitat.
"Each tree represents years of work organising expeditions, processing the collected seeds, growing them on and then planting them in Perthshire."