Raag Pug Chee รากผักชี
Cilantro with roots are available at some farmers' markets. I cut the roots (with a little bit of stem) and use the rest. It can be washed and frozen for later use without losing its potency.
Roots are used frequently in Thai cooking. It tastes milder than cilantro leaves.
Drop some cilantro roots in soup for the wonder aroma and taste.