AND THESE ARE THE HERBS WITH WHICH ONE DISCHARGES THE OBLIGATION ON PASSOVER. . .
On Passover one is required not only to eat matzah but also bitter herbs. This comes from Ex. 12:8: and with bitter herbs (m’rorim) they shall eat it. The question is, what species are specially included?
The rabbis list several, with names that were in common parlance. For example:
. . .with endives, with tamka, with harhallin, with harhabinin, and with hazeret (bitter lettuce). R. Judah said: Also with wild [field] endives and with garden endives and with lettuce. . . R. Meir said: Also with ‘aswaws, and tura and mar yero'ar. Said R. Jose to him: ‘Aswaws and tura are one; and mar is yero'ar.
Yeah. Me, too.
Eventually, it is agreed that rather than listing names (which change over time) it would be better to list observable features – and not even just a bitter taste:
Others say: Every bitter herb contains an acrid sap and its leaves are faded. R. Johanan said: From the words of all of them we may learn [that every] bitter herb contains an acrid sap and its leaves are faded. R. Huna said: The halachah is as the ‘Others’.
And, finally, a lesson is taught about the bitter herbs (maror):
R. Samuel b. Nahman said in R. Jonathan's name: Why were the Egyptians compared to maror? [and they embittered (va y’marraru) their lives (Ex. 1:14)]
To teach you: just as this maror, the beginning (top) of which is soft while its end (stalk) is hard, so were the Egyptians: their beginning was soft [mild]. but their end was hard [cruel]!
A lesson in a plant: subjugation doesn’t happen immediately, it starts with small restrictions, but ends up with great oppression.