Arnold Keeler

Arnold Keeler was a botanist working for Harrison Chase.

Biography
On Chase's orders, Keeler and Scorby went to Antarctica to steal the Krynoid pod discovered there and bring it to England. While performing experiments on the pod, it infected Keeler and he slowly transformed into a Krynoid himself. His biology changed from that of an animal to a plant. Keeler grew angry at Chase as he refused him medical attention and locked him up to study. As he fully changed he effectively ceased to exist,

Keeler grew to gigantic size, he became psychically linked to Chase, and took control of the nearby plant life as part of its plan to take over the world. It was destroyed when Major Beresford of UNIT, on the Doctor's advice, called in an aerial attack to bomb Chase Mansion. (DW: The Seeds of Doom)