Coriander: most people are familiar with the use of coriander as a herb, extensively used in Thai cooking, however the whole of the plant has a function, with both the seeds and the root an important part of some Thai curries.
Coriander/cilantro leaves: Phak chi (ผักชี). The leaves are seen often as a garnish with many Thai dishes. It is indispensable for Tom yam soup.
Coriander/cilantro root: Rak phak chi (รากผักชี). The roots of the coriandrum sativum are often used in curry pastes and certain soups such as Tom yam kung.