The qualities of 47 places identified as Important Plant Areas have been detailed in a new report to mark Plantlife Scotland's 25th anniversary.
They include Clearburn Loch which has the largest population of holy grass in southern Scotland.
The grass got its name from an old European tradition of scattering it at church doors during festivals.
Other sites include a Celtic rainforest ravine in Argyll, Crieff Woods and coastal flower meadows in the Hebrides.
The meadows, known as machair, are among the richest habitats of the 47 IPAs, Plantlife Scotland said.
Its new report aims to highlight the rich biodiversity of the sites and also the threats to them, which include over grazing by animals, burning and non-native invasive plant species.
Dr Deborah Long, head of Plantlife Scotland, said: "Our new report on Scotland's Important Plant Areas details the 47 very best places in Scotland for our wild flowers, mosses, lichens and liverworts, and include many of our most iconic landscapes.
"Put simply, they are the best places to focus our conservation resources, as they are the best places for our wild flora."
She added: "Plants and fungi, and the places they live in Scotland, continue to face ongoing pressures of changing land management, climate change and lack of resources.
"Our Important Plant Areas offer solutions to some of these issues."
The IPAs cover a total of almost two million acres.
Other sites include the Flow Country, peatland that covers large parts of Caithness and Sutherland, and Beinn Bheigier on Islay which has rare Lindenberg's featherwort moss.
Also Flanders Moss near Stirling, oakwoods on Mull, Culbin Forest near Nairn and Roslin Glen in Midlothian.
The Cairngorms, a mountain range covering parts of the Highlands, Perthshire and north east Scotland, are also an IPA.
Last year, rare communities of lichens were discovered in the Cairngorms.
Bellemerea alpina had not previously been seen in Britain for more than 30 years, despite attempts by lichenologists.
There are only two previous records of the other species, sporastatia testudinea, in Scotland.
The finds were made by Dr Rebecca Yahr, a lichen biodiversity scientist at the Royal Botanic Garden Edinburgh.