I had this book when I was a child. I learnt a fantastic amount from it, much of which I still remember over 50 years later. It is detailed, and doesn't talk down, using the Latin names of plant families, for instance, but in the context of stories. Two boys and a girl go for country walks with their neighbour, who teaches them about the plants and animals they see. Nobody worries about this, although he is male and new to the neighbourhood. I suppose by modern standards it is sexist in some ways, but one of the lessons that stayed with me is that girls shouldn't squeal at insect life!
The illustrations are exquisite.