Who must have Bitter Herbs in front of them at the Meal on Pesach Night: Pesachim 115b
Which Species Qualify
Source that it must be a vegetable: Pesachim 39a, 39b
Source that it must be grown from the ground, of a species which can be bought with the money of the Secondary Tithe: Pesachim 39a
Source for there being many species which qualify for Bitter Herbs: Pesachim 39a
Bitter Herbs is soft in the beginning, but then its stem hardens: Pesachim 39a
List of eligible vegetables: Pesachim 39a
One may even use lettuce; this is symptomatic of Hashem's mercy: Pesachim 39a
Any vegetable with sap: Pesachim 39a
Any vegetable with a green which isn't too rich: Pesachim 39a
Using the vegetable or the leaf: Pesachim 39a
If using the actual vegetable, it may be wet or dry: Pesachim 39a
If using the leaves, they must be wet: Pesachim 39b
Withered Stems: Pesachim 39b
Using a type of lettuce which grows wildly, in swamps: Succah 13a
Using a type of green called "Akravnin" or "Arkavlin," which has leaves resembling scorpions, and may be a kind of grass which grows around palm trees: Eruvin 23a, 26b