Kil'ayim (or Klayim; ) are the prohibitions in Jewish law which proscribe the planting of certain mixtures of seeds, grafting, the mixing of plants in vineyards, the crossbreeding of animals, the formation of a team in which different kinds of animals work together, and shatnez, or the mixing of wool with linen in garments.
The prohibitions are derived from the Torah in and , and the Mishnah in tractate Kilʾayim, which has a Gemara in the Jerusalem Talmud, further elaborates on the applicable circumstances.
Prohibitions The Torah (; ) lists several different examples of mixtures that are prohibited as mixed species. The halakha classifies the prohibitions under the following categories:Wald, Stephen (2007) interbreeding of animals of different species planting mixed seeds grafting of different species of trees shatnez - mixing wool and linen in garments planting grain or seed crops in a vineyard ploughing or doing other work with two different species of animal.
Permitted and forbidden instances In fabrics The 613 commandments in the Hebrew Bible forbid the wearing of shatnez – wool and linen fabrics that have been hackled together, or spun and woven together. Likewise, "intertying" sheep wool and linen together is forbidden, the two exceptions being the məʿīl or robe of the Temple priests and the tzitzit. Concerning tzitzit, the Chazal "Sages" of Rabbinic Judaism permit using wool and linen strings in tandem only when genuine tekhelet dye is available, whereas kabbalist sources go a step further by encouraging this practice. The Torah forbids only wool and linen to be worn together.Kiara, S. (1987), Hil. Kil'ayim, p. 390 Camel hair, cashmere wool, yak fiber, and the like are not prohibited from being worn with linen.Nathan ben Abraham (1955), vol. 1, s.v. Tractate Kil'ayim, chapter 8
According to Maimonides, if a Jew had purchased an all-woolen product from a gentile and wanted to ascertain whether or not it was, indeed, pure wool – without the admixture of flax-linen, its fabric could be tested by dyeing. A dye solution applied to the fabric would reveal whether it was pure wool, as wool and linen products do not retain the same shades in a dye solution.Maimonides (1974), vol. 4, s.v. Hil. Kil'ayim 10:27–28
In plantings The prohibition of sowing together diverse seedlings is derived from the biblical verse, "You shall not sow your field with two kinds of seed" (), and which prohibition has been explained to mean planting or sowing two or more diverse vegetable crops within a radius of three-handbreadths, ca. , from one another, where they draw nutrients from each other. As a first resort, however, one is to distance two or more diverse vegetable crops from each other at a remove of six-handbreadths, ca. , even if their foliage were to grow and intermix.Maimonides (1974), vol. 4, Hil. Kil'ayim 3:10Cf. Mishnah (Kil'ayim 2:10); Two or more diverse seed-crops must be distanced enough so as to be distinguished from each other as two separate plantings.Maimonides (1974), vol. 4, Hil. Kil'ayim 3:7 The prohibition not only applies to sowing together diverse kinds, but also hoeing the ground wherein diverse kinds were sown together, as well as covering them over in top soil, whether by one's foot, or by hand, or by any implement. The same prohibition applies to when they were sown together in a flower pot that was perforated at the bottom. If an entire field was planted with one kind of seedling, but next to that field was another field planted with a diverse kind (whether seedlings or a vegetable crop), the separation distance between the two fields must be 10.2 cubits, about at the very least. The laws governing diverse seed-plantings or vegetables apply only to crops grown in the Land of Israel, but do not apply to seed-crops or vegetables planted outside the Land of Israel.Aharon HaLevi (1958), mitzvah # 245Menachem Meiri (2006), p. 94, Kiddushin 39a, s.v. Likewise, these prohibitions do not apply to diverse seedlings that are planted purely for their medicinal use. (reprinted from 1922 and 1938 editions of the Hebrew Publishing Co., New York)
According to biblical exegete Nachmanides, the reason for its prohibition being that when seedlings draw nutrients from other seedlings, their properties and natural forms are changed thereby and the sower cancels thereby the fixed design and purpose of the universe.Rabbi Moses ben Nahman on the Torah, s.v. Leviticus 19:19
Diverse seed-plantings or vegetables that grew together in violation of the biblical command are permitted to be eaten,, Hil. Kil'ayim (p. 390) although the crop itself must be uprooted.Sifra on Leviticus 19:19Cf. If two diverse grain seeds (e.g. wheat and barley) were inadvertently mixed together, they must be separated before they can be sown. If, however, there were 24 parts more of one grain than the other (ratio of 24 to 1), the lesser grain is considered cancelled by the other, and may still be sown together. If there were not 24 parts more than the mixed grain, the whole must be sorted.Cf.
Specific permitted and forbidden species The first chapter of Mishnah Kil'ayim permits the growing together of certain plants, although the members of each pair belong to two different kinds. An example is certain species of Poaceae (the grass family). Wheat and tares belong to different genera (Triticum and Lolium, respectively), but resemble each other in both their seeds and their leaves. Tares are often found growing in wheat fields. Its seeds may germinate several years after being planted so that its growth could not always be prevented. This argument has been used to explain why it was not prohibited to have wheat and tares growing together in the same field.
The rabbinic treatise develops the principle that a planter should not only be concerned with the mixing together of different classes of items but also with the appearance of such intermixing, such that if the two kinds are similar in appearance but different genera, this can, at times, be tolerated.
The Mishnah in tractate Kilʾayim 1:1 explicitly permits faba beans (Vicia faba, ) and mung beans (Vigna radiata; Vigna mungo, ) to be planted together, as they are considered homogeneous. It also permits the planting of white mustard (Sinapis alba, ) and of Egyptian mustard (Rhamphospermum nigrum, ) together (Kil'ayim 1:2), as they, too, are considered to be homogeneous, despite being two different genera.Amar, Z. (2015), pp. 86-87, explaining Maimonides' commentary on Mishnah Kil'ayim 1:2. However, white mustard (Sinapis alba, ) and charlock mustard, also known as wild mustard (Sinapis arvensis, ), though also similar in appearance, may not be planted together (ibid. 1:5), as they are considered heterogeneous.Amar, Z. (2015), p. 109, explaining Maimonides' commentary on Mishnah Kil'ayim 1:5. J. Feliks maintained that while the two vegetables are similar regarding their leaves, yellow flowers, and taste, they are considered diverse-kinds because of a difference in their roots. Accordingly, the plant's roots become the ultimate criterion for determination of some diverse kinds.
Cucumbers () and muskmelons (), although they are two different species, are not considered "diverse kinds" to each other and may be planted together.Mishnah Kilʾayim 1:2 Rabbi Yehudah, disputing, says that they are considered "diverse kinds" to each other and cannot be planted together.
Although two different species, the Mishnah, Kilʾayim 1:3, permits planting together turnips (Brassica rapa subsp. rapa, ) with rapeseed (Brassica napus subsp. napus; ). Likewise, cauliflower (Brassica oleracea botrytis, ) and kohlrabi (Brassica var. caulorapa) (), although different species, are permitted to be planted together. Maimonides, in his commentary on the same Mishnah, explained the word karūb as having the Judeo-Arabic connotation of , meaning either cabbage (Brassica oleracea var. capitata) or kale (Brassica oleracea var. acephala).Amar, Z. (2015), pp. 100, 172, explaining Maimonides' commentary on Mishnah Kilʾayim 1:3.
Conversely, radish (Raphanus raphanistrum, ) and rape () cannot be planted together (Kilʾayim 1:5). Jonah maintains that while the two vegetables are similar in respect to both their leaves and their fruits, they are considered diverse-kinds because of a difference in taste. Neither can the Egyptian gourd (Cultivar of Cucumis melo, ) be planted together with the Grecian gourd (Lagenaria vulgaris, ), as they too are heterogeneous according to Mishnah Kilʾayim 1:5)
Grafting of trees
The prohibition of grafting of trees is treated on in the Mishnah (Kil'ayim 1:4).Maimonides (1974), vol. 4, Hil. Kil'ayim 1:6, who wrote: "Among trees, there is no such thing as kil'ayim except with respect to grafting." Cf. Kessar, Ḥayim (1988), vol. 2, p. 344, s.v. on Mishneh Torah, Hil. Kil'ayim 3:4. Rabbi Ḥayim Kessar writes there: "Such is the case with trees, where there are two trees similar in appearance to each other, etc. Mishnah ibid., and it is plain that it refers to a tree with respect to grafting, as I shall explain in what follows." The matter of tree grafting is evinced also by the Jerusalem Talmud (Kil'ayim 1:4), in a discussion on the same Mishnah, where after citing cases of grafting of two different kinds of trees named in the Mishnah, the trees were then cut down. The Talmud also brings down examples of hybrid fruit caused by grafting two dissimilar trees together. The prohibition applies to all trees, whether growing within the Land of Israel or outside. Among trees, while it is permissible to grow two different kinds of trees in close proximity to each other, it is forbidden for an Israelite (or a gentile working on behalf of an Israelite) to graft the branch (scion) of one tree onto the stump of another tree to produce thereby a hybrid fruit if the trees are not one and the same kind. Quince (Cydonia oblonga, ) is named as an exception, for if a branch taken from it were grafted onto a stump belonging to hawthorn (Crataegus azarolus, ), although they are two different species, it is permitted since they are considered related in Mishna, Kil'ayim 1:4.On the definitions of these words, see: Amar, Z. (2015), pp. 132-133, 118 Likewise, to graft the branch of Krustemelin (said to be the "Calaprice pears")Thus explained by Isaac ben Melchizedek's Mishnah Commentary (1975:79), s.v. Kila'yim 1:4. On this fruit, see Pere calaprice. onto the rootstock of an ordinary pear (Pyrus communis) is permitted. However, apple (Malus domestica, ) grafted onto medlars (Mespilus germanica, ),Definition here follows that of Maimonides. However, Nathan ben Abraham explains חֻזרד as being a cultivar of pear. or peach (Prunus persica, ) grafted onto almond trees (Prunus dulcis, ), or jujube (Ziziphus jujuba, ) grafted onto Christ's thorn jujube (Ziziphus spina-christi, ), although similar in appearance, are "diverse kinds."Mishnah (Kil'ayim 1:4)On the definitions of these words, see: Amar, Z. (2015), pp. 76, 150, 157. In Modern Hebrew, the word shezif now means "plum" (Prunus domestica subsp. insititia, or simply known by the synonym Prunus insititia), although in today's meaning, it is not to be confused with the Mishnaic meaning. The fruit produced by grafting the bud of one dissimilar tree onto the rootstock of the other are permitted to be consumed by Israel,Babylonian Talmud (Hullin 115a)Meiri (2006), p. 94, Kiddushin 39a, s.v. הרכבת אילןKiara, S. (1987), Hil. Kil'ayim, p. 394 although the trees themselves, according to some authorities, are not permitted to be maintained.Tosefta (Kil'ayim 1:3); Jerusalem Talmud (Kil'ayim 1:4). Cf. Jacob ben Asher, Arba'ah Turim (Yoreh De'ah 295:7); Halberstam, C. (2002), vol. 1, Yoreh De'ah, responsum # 60 (pp. 239–243)Cf. Chazon-Ish (1994), p. 46a–b [2:9], who brings down a rabbinic dispute over whether trees grafted by way of transgressing the prohibitive command require uprooting, or whether they can be maintained.