Any flowering plant of the genus Primula, one of 28 genera of the family Primulaceae. Primula includes 490–600 species, which occur chiefly in the Northern Hemisphere in cool or mountainous regions. The plants are low-growing, usually perennial herbs; a few are biennials. Most species grow 25–50 cm (10–20 inches) tall, but some are as short as 5 cm and others as tall as 120 cm. Many species are cultivated for their attractive, five-petaled flowers, which may be red, pink, purple, blue, white, or yellow. Pimpernels are also in the primrose family. The evening primrose (family Onagraceae) is not a true primrose.