The Bedside Book Of The Garden by Dr D G Hessayon
This book has in fact been next to my bed for, dare I say it, over a year!
I quite frequently start reading it in bed and the chapters are just the right length for a little peep before dropping off. It has lots of interesting bits of information and trivia in it, ranging from famous plant finders, to Kew Gardens, to unusual plants. It really is an ideal book to dip into now and then, and unlike a novel you can put it down for weeks at a time and come back to it.
The style of writing is plain, informative and very readable. I received it as a gift, and would recommend it for the gardener in the family this Christmas. (Or treat yourself!)