Because it represents bitterness, the bitterness of the Jews who were enslaved in Egypt. Romain lettuce specifically is used, because if left in the ground it gets bitter, and the Jews slavery was the same way. First they were coerced to helping out to build in Egypt, for a good salary, and slowly were forced into slaves.
Certain types of lettuce are used as the bitter herb which forms an important symbolic part of the Seder. Bitter herbs represent the bitterness of the Hebrew's enslavement in Egypt, as is recalled in Exodus 1:14: "And they embittered (ve-yimareru וימררו) their lives with hard labor, with mortar and with bricks and with all manner of labor in the field; any labor that they made them do was with hard labor".
the bitterness of slavery
The seder plate. See also:More about the Seder
A seder plate is placed on a dining table.
The Seder plate is a special plate used during the Passover Seder meal in Jewish tradition. It holds symbolic foods that represent various elements of the Exodus story and the Jewish people's journey to freedom. Common items on the Seder plate include bitter herbs, a roasted shank bone, a mixture of fruits and nuts, and a boiled egg.
the seder plate has six iteams on,
The Seder Plate is a special plate for holding the symbolic foods used during the seder. Pieces of the symbolic foods are distributed to everyone during the course of the seder. Traditionally, the person leading the seder is the only one with a Seder Plate. However if there are many guests, additional Seder Plates can also be set on the table.
Some say that it has no special meaning, being just a container for the meaningful items. Others say that the plate itself represents Malchut (God's kingship).
It depends on the Seder plate, but most Seder plates label the spots where all the special foods go.
during a passover seder.
In the seder meal the parsley, or other type of bitter herb, represents the bitter taste of slavery and affliction. In some homes parsley is used because it looks similar to a flail.
seder plate
seder plate