Poppy seeds are used whole or ground as an ingredient in many foods. You can also make poppyseed oil. And opium, but we are not too concerned about that here 😉 The poppy plant is a flower from the family Papaveraceae (poppy family).
Poppy seeds are included in the category of kitniot as defined by the Shulchan Aruch Yoreh Deah 297:3 for kil’ayim, forbidden mixtures (see our discussion of sesame). The Rambam writes in connection with Pesach that "it is permissible to place spices, sesame seeds, poppy seeds, and the like into dough" (Mishne Tora, Chametz uMatza 5:20). Of course, that was before kitniot, but while the Rema added for mustard (just before, in 5:19) that mustard is considered kitniot, he did not add the same comment for sesame or poppy seeds (or Chabad didn’t translate it, which I doubt).
Still, poppy seeds are on pretty much every list (e.g., OU, Star-k, Kashrut.com, cRc Guide). Why? Probably just because they are seeds – although they are so small, one could argue they are spices and should therefore permitted (see our discussion on spices).
- Danger of chametz traces: Don’t think so.
- Danger of confusion with chametz (raw): No.
- Danger of confusion with chametz (processed): No.
- Botanical categorization: Papaveraceae, flower.
- Known in 13th century: Yes.
- Verdict: Not kitniot.