Seed, not leaf
Semilla de cilantro is the whole dried seed of Coriandrum sativum, 7 oz to the bag. In English it is coriander seed. In a Mexican kitchen the seed goes into menudo, pozole and caldo de res.
Toast the seeds dry in a skillet until you can smell them, then crush them in a molcajete just before they go into the pot. The bag describes the flavor as citrusy, sweet and a touch spicy, and crushing at the last minute is how you keep that in the broth. Seven ounces of seed covers a long run of Sunday pots of pozole.
In the YERBERO herb shelf, Semilla de cilantro is filed under C in the herbolario A–Z, next to Cuachalalate.