THEY work in the dead of night, armed with seed bombs, chemical weapons and pitchforks. Their aim: to beautify.
An army of self-styled Guerrilla Gardeners is growing across the world, fighting to transform urban wastelands into horticultural havens.
To document and encourage their victories, one of the movement's leaders has written a handbook. On Guerrilla Gardening, by Richard Reynolds, defines the activity as "the illicit cultivation" of someone else's land.
"Our main enemies are neglect and scarcity of land," said Mr Reynolds, 30, a former advertising employee who wrote the book after his website, guerrillagardening.org, became a global focal point for activists.