One who sells a field has sold the ungrafted carob tree and the virgin sycamore [a young sycamore not yet cut]. And when he said to him, "it and everything in it," then all of these are sold. In either case he has not sold the grafted carob tree or the trunk of the sycamore [established trees], for Scripture says, "and the field of Ephron arose" (Genesis 23:17). Whatever needs a [surrounding] boundary is included; these that do not need a surrounding boundary are excluded. From here we learn [the law of] boundaries from the Torah.
What Passes When a Field Is Sold and What Stays Behind
Yalkut Shimoni on Torah 102:22
הַמּוֹכֵר אֶת הַשָּׂדֶה, מָכַר אֶת הֶחָרוּב שֶׁאֵינוֹ מֻרְכָּב וְאֶת בְּתוּלַת הַשִּׁקְמָה וּבִזְמַן שֶׁאָמַר לוֹ הִיא וְכָל מַה שֶׁבְּתוֹכָה הֲרֵי אֵלוּ כֻּלָן מְכוּרִין. בֵּין כָּךְ וּבֵין כָּךְ לֹא מָכַר חָרוּב הַמֻּרְכָּב וּסְדַן הַשִּׁקְמָה, דְּאָמַר קְרָא וַיָּקָם שְׂדֵה עֶפְרוֹן וְגוֹ' מִי שֶׁצָּרִיךְ לִגְבוּל [סָבִיב] יָצְאוּ אֵלוּ שֶׁאֵינָן צְרִיכִין לִגְבוּל סָבִיב מִכָּאן לְמֵיצָרִים מִן הַתּוֹרָה.