Here is a statement from the Green Belt Movement which she founded:

Wangari Muta Maathai (1940-2011)

It is with great sadness that the family of Professor Wangari Maathai announces her passing away on 25th September, 2011, at the Nairobi Hospital, after a prolonged and bravely borne struggle with cancer. Her loved ones were with her at the time.

Professor Maathai’s departure is untimely and a very great loss to all who knew her—as a mother, relative, co-worker, colleague, role model, and heroine; or who admired her determination to make the world a more peaceful, healthier, and better place.

Prof. Wangari Muta Maathai started the Green Belt Movement in 1977, working with women to improve their livelihoods by increasing their access to resources like firewood for cooking and clean water. She became a great advocate for better management of natural resources and for sustainability, equity, and justice.

Prof. Maathai leaves her three children—Waweru, Wanjira, and Muta—and a granddaughter, Ruth Wangari. They are truly very grateful for all the prayers and support they have received.