Kilayim 1:4

Among trees, domestic and wild pears are not kilayim with one another, nor are quince and malus (which are both members of the apple family). Apples and crabapples are kilayim with one another, as are peaches with almonds and jujubes with lotus, even though these species do have some similarities with one another.

Kilayim 1:5

Other species that are similar but nevertheless kilayim with one another include: horseradish and radish; mustard and wild mustard; Greek gourds with both Egyptian gourds and bitter gourds.