We live near a public thoroughfare where there are shops and stores. Near one store there are some aromatic bushes growing. I’m not sure who it belongs to-it may have possibly been planted by the city government. Is this considered public property? Is it permitted to pick some leaves for havdalah every week from these bushes?
It is permitted to take leaves (a small amount) from bushes in the public domain.
In principle, it is forbidden to steal public property, including property in the public domain.
Therefore, it is forbidden to take a rose bush from the public domain, and to transfer it to one’s house.
However, the Beis Yosef (Choshen Mishpat 359:1) notes that some authorities write that it is permitted to take chips of wood from somebody’s fence, because people are not makpid (particular) about it. The Beis Yosef adds that even this is frowned on by the Yerushalmi as “midas chasidus,” because if everybody would do it, there would be no fence left.
The explanation of why there is no prohibition of gezel (theft) for something that people are not particular about is given by the Noda Biyhuda (Kama Even Ha-Ezer 59) as the mechanism of hefker, whereas the Avnei Milu’im (28:49) writes that it is considered a “gift” (see also Nachal Yitzchak, Choshen Mishpat 6, and see Shulchan Aruch, Even Ha-Ezer 28:18).
In general, the municipalities that plant bushes in the public domain are not “particular” about people taking leaves, provided this the amount is reasonable, and there is no danger to the wellbeing of the bush/tree.
The concern that there will be no bush left if everybody does it is not much of a concern — the number of people interested in taking leaves for havdalah is limited, and it stands to reason that the bush is not in danger — so that the midas chasidus of the Yerushalmi might also not apply. [There is also room to suggest that the Yerushalmi won’t apply to public property.]