משנה על שביעית 2:1

They may not sow different species of seeds in one bed, but they may sow different species of vegetables in one bed. Mustard and small polished peas are a species of seed; large peas are a species of vegetable. If a border was originally a handbreadth high and then it fell in height, it remains valid, since it was valid at the beginning. A furrow or water channel which are a handbreadth deep, it is permitted to sow three different species of vegetables, one on one side, one on the other side, and one in the middle.

Rabbi Yose says: Anything stewed with [terumah] beets becomes forbidden, because they impart a flavor. Rabbi Shimon says: cabbage from a field artificially irrigated [that is stewed] with [terumah] cabbage from a field watered by rain, is forbidden because it absorbs. Rabbi Akiba says: all things cooked together are permitted, except those with meat. Rabbi Yohanan ben Nuri says: liver renders other things forbidden, but does not become forbidden, because it gives off [flavor] but does not absorb.