On yesterday’s daf we learned how the plant ḥatzav – Urginea maritima or sea squill – may be used to demarcate the boundaries of a field. The Gemara on today’s daf asks mai ḥatzuva? – literally “what is ḥatzav?” In response, Rav Yehuda quotes Rav as saying that Yehoshua used it to demarcate the boundaries of the land of Israel.
The Rashbam explains that the Gemara is not asking for a description of the plant, rather what significance will there be to a border established by the use of ḥatzav. The response offered by Rav Yehuda indicated that the ḥatzav is a very reliable method of establishing boundaries, as we find that it was used by Yehoshua in marking the boundaries in Israel; clearly it can be used in clarifying mundane land issues, as well.
The Gemara in Massekhet Beitza (25b) argues that the ḥatzav plant “cuts down the legs of evildoers.” Since its roots grow directly downwards without spreading in any other direction, it serves as a reliable marker of the border between fields and acts as solid proof against someone who is masig gevul – who tries to claim a piece of his neighbor’s land.
The Gemara brings a number of other statements by Rav Yehuda quoting Rav in connection with the inheritance of the land of Israel following the exodus from Egypt. For example, Rav Yehuda quotes Rav as teaching that the cities enumerated in Sefer Yehoshua are only those that were found on the borders. The Rashbam explains that the Gemara is explaining why only some cities are mentioned, while others are left out entirely; the ones that are mentioned are those that demarcate the borders between the different tribes. The Ritva argues that they are the cities that were on the “international border,” i.e. those that separated between Israel and neighboring countries.