The tropaeolaceae (nasturtium) family contains just one genus, tropaeolum, of which a single (introduced) species is found in the US, mostly along the California coast. Plants are native to central and south America; they are annual or perennial herbs, with fleshy stems and leaves, prostrate stems and simple leaves. Flowers are large and colorful, usually bilaterally symmetric, formed of five sepals, two projecting backwards into a spur, and five petals, narrow at the base. The upper two petals are different in shape to the lower three. At the center are eight stamens, unequal in size.