Although presented as an ABC book this this really a guide to wildflowers aimed at more advanced readers. The text is is small in size, complex in content, and hand-written in calligraphy (as well as not particularly sparkling -- Cameron is an artist, not a writer) and would certainly be too difficult for a child at the alphabet-learning stage. I suppose with a younger child one could skip the text and just pair the names of flowers with pictures, although even that would probably not be too engrossing unless one lived in the area where these flowers grow. Otherwise they are unfamiliar plants with long, unfamiliar names and places. "I picked this Jack in the Pulpit at Old Allengrange," eg.
Cameron made this book by hand, for her grandchildren, and I'm sure for them it was lovely and reflected places they knew and associated with their beloved grandmother. For a general audience I would recommend this more for people interested in wildflowers or botanical illustration than for children.