Arctic alpines – such as alpine foxtail, drooping saxifrage and snow pearlwort – are relics of the last ice age and many depend on snow cover to thrive.
In Scotland, they can only be found in the most mountainous parts. But there is evidence recent mild winters have forced a decline.
They depend on deep and persistent snow to counter fierce winds and severe frosts. National Trust for Scotland conservation specialist Helen Cole said: "One cold month is unlikely to make much difference in the long term but it does give some hope that we may occasionally get the harsh weather to which these beautiful rarities are supremely adapted."