The Accelerating Bamboo is a plant mentioned in The Compleat Discworld Atlas and may in context be native to the Agatean Empire. it is of interest to horticultural research scientists at Cabbage Down and it is believed they are attempting to cross it with the Sledgehammer shrub to create a hybrid that may have useful applications to civil engineering, military engineering, and presumably to the Assassins' Guild.
What is so special about this plant may only be inferred from the brief mention in The Compleat Discworld Atlas, but a literary parellel is in Philip José Farmer's magnificent Riverworld series, where the entire human race discovers the Heaven to which they have been ressurected is a long winding river on an unguessably large Riverworld. The river valley is flanked by acres and acres of really fast-growing bamboo; the ressurected humans still need some sort of renewable wood resource for building shelters, making boats, and general utility. The bamboo grows incredibly quickly and however much is harvested, there will be more coming along within days growing from seed to maturity. The speed of its growth on Discworld can only be guessed at.