Wolfweed

The Wolfweed were domesticated mobile plants native to Chloris.

Biology
Wolfweed were round, green plants covered in vines and leaves. They moved by rolling, but could also jump to reach their prey. Wolfweed captured their prey by smothering them in packs and wrapping them in a grey, web-like substance. They had an animal-like mentality and hunted down their prey. (DW: The Creature from the Pit)

History
Lady Adrasta had several Wolfweeds specially grown in nurseries for tracking and attacking purposes. They were kept in order by the Huntsman who commanded them with a whip.

When Karela's party encountered the Fourth Doctor, the Huntsman had the Wolfweeds sneak up on him and attack. They captured him and then released him on the Hunstman's command. They again helped attack K9, disabling him after he killed one of their number. After Adrasta was exposed, the Wolfweeds helped Erato kill her. As they did so, Erato ate them too. (DW: The Creature from the Pit)

Behind the scenes

 * The Wolfweeds were designed by Matt Irvine. They were remote controlled and used an ingenious method of propulsion. Inside each Wolfweed was a motor, powered by a heavy lantern battery. The battery itself acted as a counter-weight. When the motor turned, the battery moved making the Wolfweed move forwards. The gearboxes had a tendency to burn out causing delays in filming.