The green living roof at the California Academy of Sciences completed in 2007 has 2.5 acres of local, native plants and was built primarily for research and education purposes. (Image courtesy San Francisco Planning Department)

The green living roof at the California Academy of Sciences completed in 2007 has 2.5 acres of local, native plants and was built primarily for research and education purposes. (Image courtesy San Francisco Planning Department)

The green living roof at the California Academy of Sciences completed in 2007 has 2.5 acres of local, native plants and was built primarily for research and education purposes. (Image courtesy San Francisco Planning Department)