Coriander is the seed from which cilantro stems and like the leaves of the plant are used in Mexican, Indian, Thai and Chinese cuisine. Seeds can be gently crushed to break the outer husk and soaked 24 hours in advance to increase germination. Collect leaves as needed for cilantro. Once the plant bolts collect the seeds for coriander. Cilantro is an annual, but will often reseed itself for the next year.