Hi, Another vote for Hostile Habitats. Very informative at the right level I'd say. For other bits and bobs that need identifying I use the net. Field Studies Council produce good waterproof keys too, which you can take with you easily, but I prefer the photo and do the rest at home method.
Well, you live and learn - I hadn't realised that identifying flora was part of ML training. But, given what different types of plant cover can tell you about the landscape, I can see the sense in it.
Having a basic grasp of flora can be quite useful when you're trying to 'read' your way across country. Heather, for instance, should indicate reasonably dry ground. Spahgnum moss, on the other hand, should be avoided, regardless of the fact that it looks as innocuous as a bowling green.
As for heather... most of the heather you see is ling. Bell heather is a dead give-away because, like leg-pulling, it quite literally has bells on!
Edward, Octopus Books Ltd.59, Grosvenor Street .London W1 Mountain Flowers.Over 100 illustrations in colour. Nothing technical just identity and habitat.