'Root' in the Bible

Already now the ax is positioned at the root of the trees; therefore every tree not producing good fruit is cut down and thrown into the fire.

But [when] the sun rose it was scorched, and because it did not have [enough] root, it withered.

But he does not have a root in himself, but {lasts only a little while}, and [when] affliction or persecution happens because of the word, immediately he falls away.