Mishnà su 'Uqsin 1:13

For Rabbi Meir used to say: anything that is normally [sold] by counting causes [a mixture] to become consecrated [in even the smallest amount]. But the sages say only six things consecrate [a mixture in even the smallest amount], and Rabbi Akiba says seven [things]. And these are they: Nuts with soft shells; badan pomegranates; stopped-up casks; beet shoots; cabbage-heads; Greek pumpkins. Rabbi Akiba says: also loaves [baked by] a householder. To those to which orlah applies [they prohibit the mixture] as orlah, [to those of which] kilayim of the vineyard apply [they prohibit the mixture as] kilayim of the vineyard.