Fabaceae is one of the largest plant groups in the British Isles, with around 90 species. Also known as the pea, or bean family, the great majority have distinctive flowers formed of five petals, of three types; the banner (or standard) at the top, usually the largest, two wing petals at either side and two keel petals underneath, often partially fused. Within the corolla, usually rather hidden, are ten stamens and one pistil. The corolla is supported by a five-lobed calyx. Leaves are pinnate or trifoliate. Fruits are pods, usually relatively long and narrow, containing a small number of seeds.