Kislev

Kilayim of trees is the prohibition against grafting a branch of one species of fruit tree onto a different species of tree. For example, grafting an apple branch onto a pear tree is forbidden. This mitzvah applies specifically in the Land of Israel, and is one of the mitzvot that depend on the Land. The Sages taught that even one who grafts a branch is liable, and even one who maintains a grafted tree is commanded to uproot it. Kilayim of trees teaches that the integrity of each species is a divine principle, and the farmer in the Land of Israel is commanded to honor the boundaries of creation even in his orchard.