MISHNA: These are the types of grain with which a person fulfills his obligation to eat matza on the first night of Passover: With wheat, with barley, with spelt [kusmin], with rye [shifon], and with oats [shibbolet shu’al]. And one fulfills his obligation by eating not only matza made from properly tithed grains, but even with matza made from doubtfully tithed produce, and matza made with first tithe from which its teruma was already taken, or second tithe and consecrated food that were redeemed. And priests may eat matza prepared from ḥalla, the portion of dough that is given to priests, or with teruma, as priests are permitted to eat these portions. However, one may not fulfill one’s obligation to eat matza made with untithed produce, nor with matza made from the first tithe from which its teruma was not separated, nor with matza made either from the second tithe, nor from consecrated grain that was not redeemed. With regard to one who prepared loaves of matza that are brought with a thanks-offering, or to the wafers brought by a nazirite, the Sages drew the following distinction: If he prepared them for himself, then he does not fulfill his obligation to eat matza with them. However, if he prepared them to sell them in the market to those who require these loaves or wafers, one fulfills the obligation to eat matza with them. GEMARA: The Gemara identifies the species mentioned in the mishna. One of the Sages taught in the Tosefta: Spelt is a type of wheat, while oats [shibbolet shu’al] and rye [shifon] are a type of barley. The Gemara translates the lesser-known species into the vernacular Aramaic: Spelt is called gulba; rye is dishra; and oats are shevilei ta’ala. The Gemara infers: These species, yes, they may be used for matza; however, rice [orez] and millet [doḥan], no, they may not be used. The Gemara asks: From where are these matters, that matza cannot be prepared from rice or millet, derived? Rabbi Shimon ben Lakish said, and likewise a Sage of the school of Rabbi Yishmael taught, and likewise a Sage of the school of Rabbi Eliezer ben Ya’akov taught that the verse states: “You shall eat no leavened bread with it; seven days you shall eat with it matza, the bread of affliction” (Deuteronomy 16:3). This verse indicates that only with substances which will come to a state of leavening, a person fulfills his obligation to eat matza with them, provided he prevents them from becoming leavened. This excludes these foods, i.e., rice, millet, and similar grains, which, even if flour is prepared from them and water is added to their flour, do not come to a state of leavening but to a state of decay [siraḥon]. The Gemara notes: The mishna is not in accordance with the opinion of Rabbi Yoḥanan ben Nuri, who said: Rice is a full-fledged type of grain, and one is liable to receive karet for eating it in its leavened state, like other types of grain. As it was taught in a baraita: Rabbi Yoḥanan ben Nuri prohibits eating cooked rice and millet on Passover, due to the fact that they are close to being leavened.

(1) The prohibition against chametz applies only to the five species of grain. They include two species of wheat: wheat and spelt; and three species of barley: barley, oats, and rye.
However, kitniyot - e.g., rice, millet, beans, lentils and the like - do not become leavened. Even if one kneads rice flour or the like with boiling water and covers it with fabric until it rises like dough that has become leavened, it is permitted to be eaten. This is not leavening, but rather the decay [of the flour].

(1) These are the things through which one fulfills the obligation of [eating] matza: wheat, barley, spelt, oats and rye - and the custom is to take wheat initially (Maharil) - but not rice and other types of legumes [kitniyiot], and these also do not come to be leavened and it is [so] permitted to make a cooked food from them. REMA: And some forbid [it] (Tur and Hagahot Maimoniot and Mordechai on the Chapter [entitled] Kol Sha'ah). And the custom in Ashkenaz is to be strict [about this], and one should not change [it]. However, it is obvious that they do not render a cooked food forbidden after the fact if they fall into it. And so [too] is it permitted to light with oils that are made from them and [these oils] do not render a cooked food forbidden if they fall into it. And so [too] is it permissible to store types of legumes in the home (Terumat HaDeshen, Section 113). And the seed of dill (Maharil) and anise and coriander are not types of legumes and it is permissible to eat them on Pesach, and so does it appear [correct] to me.