The Chimpanzees of Happytown by Giles Andreae and Guy Parker-Rees.
Andreae and Parker-Rees create picturebooks filled with vibrant color and very cool animals.  Their newest is no different.  The chimpanzees of Drabsville, USA live in a grey world with no trees, no parks, just concrete.  But then Chutney, a world-traveling chimp arrives with a seed.  Unfortunately, when he plants it the mayor notices and orders the plant cut down and Chutney thrown into jail.  But all is not lost.  The boy and girl chimps next door to Chutney continue to water the seed and it turns into a huge plant that comforts Chutney in his jail cell.  When Chutney is released from jail, he calls for the population of Drabville to rebel.  The colors become wild pinks, purples and oranges filled with a profusion of flowers and trees. 
The book may be a little obvious for parents, but I have shared it with children and they all adored the message and the transformation.  The book ends with:  “And things will always blossom if we dare to set them free.  It’s no different for a little flower than for a chimpanzee.”  This book has a strong environmental message making it a nice addition to environment or nature units for preschoolers and kindergarteners.