Cilantro & Coriander : Slow-Bolt
Slow-bolt, spicy cilantro
Deliciously spicy, pungent, bright green leaves essential for Mexican and Asian dishes. This slow-bolt strain holds better than any other at the leaf stage.Apiaceae Coriandrum sativum
If left alone this insect-pollinated plant will eventually produce seed and may even self-sow. There aren't many varieties, so you probably don't have to worry too much about cross-pollination.
Gather the seed heads as the seeds start to turn brown and leave them to dry in a paper bag in a warm place.