Growing to 2 m (6.6 ft) tall, it is a twining herbaceous perennial with grey-green leaves and, in late summer, bright magenta-pink flowers, the central keel a darker red. Unlike its cousin, the annual sweet pea (Lathyrus odoratus), it is unscented. Once established it is a robust plant with the ability to scramble into other shrubs and trees.[3] It is very hardy, down to −20 °C (−4 °F), so is capable of surviving conditions in most temperate regions of the world.