Vietnamese coriander

P. odorata is a spreading herbaceous perennial 45cm high, rooting at the nodes, with reddish-purplish stems, aromatic, lance-shaped leaves which are green with a dark purple-brown chevron, and spikes of tiny pink flowers in late summer which rarely appear, however, in temperate areas; the leaves are used in south-east Asian cooking, and have a pungent, coriander-like aroma when young, becoming more biting and hot as they age