Can a concept book win the Caldecott? I'm pretty sure none have yet.

Can a concept book win the Caldecott? I'm pretty sure none have yet. No alphabet books, counting books or color books. What about this one -- a color book about just one color?
Putting it that way makes
Green sound too simple. Trust Seeger to add layers of complexity and meaning, but with a light touch. In a rhyming text, just two words per spread introduce different shades of green: "forest green / sea green / lime green / pea green." Cleverly placed die cuts hint at the next shade and each cut does double duty after the page is turned. Seeger knows just when to break the pattern, placing the text in a window for "jungle green" and "khaki green," each word written with sneakily camouflaged brush strokes.
I would have been satisfied if she had left it there -- seemingly simple, cleverly designed, appropriate for a wide range of ages. But near the end she adds yet another layer with "all green / never green / no green / forever green." What's going on here? Aren't we doing shades of green? "Never green" shows a stop sign -- "that's RED!" you can hear the three-year-olds saying. But older kids who know about global warming and other ecological worries might see it differently. The "no green" spread innocently shows a winter scene, but next we see a kid tending to a small plant with no words of explanation. This break in the pattern again indicates there's something more going on. Sure enough, the next spread ("forever green") shows a man and child looking at a big tree just where the plant was on the previous spread. And that's all. The end. Ready for questions and discussion: Is the man at the end actually the boy all grown up?
I'm hoping everyone reading this post is familiar with Seeger's painting style. If you're not, the cover above gives an inkling of her thick paint applied with both brush and palette knife. The impasto is so luscious that I want to stroke the page to feel the paint's texture.
I'm amazed Seeger hasn't won a Caldecott yet, but the award does seem to go to books that are more obviously impressive in some way. While her style is painterly, she never shows off. She keeps her compositions clean and effortless-looking. But I think what I like most about Seeger's concept books is that she trusts the audience's intelligence, truly understanding that they are the last step in bringing a book to life.
In the comments about
Extra Yarn, someone brought up a small mistake. There's one in
Green, too, and I wonder if this will stop the committee from going all the way. On the "glow green" spread, all but one of the the many little holes meant to show fireflies at night are perfectly placed over the brightest green bits on the following spread. Will this be a deal breaker for the committee? I hope not. It certainly wasn't for all the journals who gave it a star.