1,141. Maror
Chometz u’Matzah 7:13
The Torah considers five species to be maror. These are difficult to identify but they apparently include (Romaine) lettuce, endives and horseradish among them. If a person ate an olive-sized portion of any of these, or of all five of them combined, he has fulfilled his obligation. This applies so long as they are still fresh; one can fulfill his obligation with the plant’s stem even if it is dried. One cannot fulfill his obligation of maror with a boiled, pickled or cooked vegetable.
Chometz u’Matzah 8:1
The order of the mitzvos on the night of 15 Nisan is as follows: First, a cup of wine is mixed for each person. They recite the bracha of hagafen, kiddush and shehechiyanu, after which they drink. Next, one recites the bracha of al netilas yadayim and washes his hands. A set table is brought [their tables were like tray tables], containing maror, another vegetable, matzah, charoses, and (in Temple times) the Passover offering and the holiday offering. Nowadays, we place two types of meat on the table, in commemoration of the Passover offering and the holiday offering, respectively. [Our custom is to use a roasted shankbone and egg for this purpose.]