Kyropite

Kyropites were parasitic plants native to the planet YT45.

The plants could emit a soporific gas that put nearby fauna in a dreamlike state. The kyropites would then feed telepathically on the alpha waves produced. If close enough, the plants would extend tendrils and also consume the fauna physically. The Fifth Doctor, Peri and Erimem encounter them on YT45. (AUDIO: The Mind's Eye)

In his sixth incarnation, the Doctor (with Charley Pollard) find the plants again inside an ice planet. A group of Thals discovered a Dalek experiment on the planet to use the kyropites to brainwash people. One of them, Murgat, managed to escape the effects of the plants. However, he became a Thal-Kyropite hybrid in the process. He then used them to try to change the Daleks' nature to good. (AUDIO: Brotherhood of the Daleks)