"THE GREAT JERUSALEM CAPER." That is, the caper bush. Excerpts from the Jerusalem Post article:

This invincible plant is the caper bush, Capparis spinosa.

In the Talmud, Rabban Gamliel pointed to the caper as an example of what all plants will do when the Messiah comes - namely, produce new flowers and fruits daily. Capparis is the Greek word for caper; spinosa means spiny, and refers to the thorns that grow along the plant's stems.

The caper bush is native to Jerusalem, where it is found growing in crevices of ancient stone walls. At more than 50 feet above ground level, caper bushes can even be found cascading out of the cracks in the Western Wall.

[...]

There is another significant site where caper bushes grow. It is Masada National Park, near the western edges of the Dead Sea.

During Israel's great revolt against Rome in the first century, a group of zealots, determined to resist conquest, took refuge in Masada, a fortress atop an isolated mountain. For seven months, 15,000 Roman soldiers laid siege to Masada, which was defended by 967 men, women, and children. When they could no longer hold out against Rome, this band of zealots chose to die by their own hands rather than be taken captive, forced to give up their religion, and live as slaves. It is only natural that the caper bush, the world's most defiant plant, flowering luxuriously in the middle of summer, should flourish atop Masada.