Pumzi is a Kenyan science-fiction short film written and directed by Wanuri Kahiu. It was screened at the 2010 Sundance Film Festival as part of its New African Cinema program.
Here’s a description of the film:
In a dystopian future 35 years after an ecological WWIII has torn the world apart, East African survivors of the devastation remain locked away in contained communities, but Asha, who works as a museum curator, in possession of a germinating seed struggles against the governing council to bring the plant to Earth’s ruined surface.
You can watch the film at the link.