Gregory the Dialogist

His roots will be wrapped about the heap of rocks, and he will dwell among the stones. For what do we understand by the name of 'roots' save the hidden thoughts, which issue forth out of sight, but rise up in the display of works in open day? as it is also said by the Prophet concerning the seed of the Word, And the remnant that is escaped of the house of Judah shall again take root downward and bear fruit upward. …

Morals on the Book of Job, Book VIII ↗

Thomas Aquinas

Second, confidence may be placed in the rush in other ways, i.e. either from being rooted bunched together with many others or from the firmness of the place where it grows when it is born in a rocky place. So he consequently says, "its roots," of the rushes, "were crowded together on a heap of stones," as the roots of many papyrus are intertwined together. He expresses the first idea with this. …

Commentary on Job ↗