Artificial ivy

Artificial ivy was used by the Kraals in their reproduction of Devesham on Oseidon. The Kraal androids tied the Fourth Doctor up with it in the village centre while Styggron set a matter dissolving bomb at his feet. Sarah Jane Smith attempted to cut him free but found it to be "as strong as steel". She used the sonic screwdriver, setting it, per the Doctor's instructions, to theta omega, allowing her to cut through the ivy. The pair narrowly escaped the blast. (TV: The Android Invasion)