Gunnera is a genus of herbaceous flowering plants, some of them gigantic. The genus is the only member of the family Gunneraceae.
The 40-50 species vary enormously in leaf size. Gunnera manicata, native to the Serra do Mar mountains of southeastern Brazil, is perhaps the largest species, with leaves typically 1.5-2 m (5-6 ft) wide, but exceptionally long, up to 3.4 m (11 ft), borne on thick, succulent leaf stalks (petioles) up to 2.5 m (8 ft) long. It germinates best in very moist, but not wet, conditions and temperatures of 22 to 29 °C.