K is for... Krynoids

Carnivorous form of intelligent plant-life which is hostile to animal kind. Little is known of their origins though it is believed that they come from a planet whose surface was prone to volcanic upheavals, which would send Krynoid seed pods shooting into space. In this way they could establish themselves on other planets and consume all its fauna. The pods always travel in pairs, suggesting that they originate in some sort of sac which decomposes, or they are connected by a cord of some other vegetable manner which also rots after they have made landfall.

Another ability shown by adult Krynoids was to be able to control local flora and turn it against people and animals.

A research party discovered a seed pod in Antarctica and notified the World Ecology Bureau. They in turn contacted UNIT who sent the Doctor and Sarah Jane Smith to investigate. Despite the Doctor's warning not to touch the pod until he had got there, the scientists thawed it out and fed it under UV light. A tendril emerged and fixed itself to the arm of a man named Winlett, infecting him. He rapidly began to mutate into a Krynoid.

The Doctor advised that the source of infection - his arm - be cut off but before this could happen he broke out of the sickbay and killed a colleague. The Doctor, meanwhile had located the second pod. A corrupt member of the Bureau had informed the plant-obsessed millionaire Harrison Chase about the initial find and he had sent one of his henchmen - Scorby - to the Antarctic to retrieve the pod, along with a botanist named Keeler. Scorby planted a bomb after stealing the second pod, which destroyed the Winlett-Krynoid before it could attain adult status. It was still vaguely human shaped, whereas adult specimens were a gigantic mass of vegetable matter, covered in thick tendrils.

Back in England, Chase attempted to use Sarah as host for the second pod but the Doctor's intervention caused Keeler to become infected instead. Chase fed him raw meat and he rapidly mutated into a full Krynoid, hundreds of feet tall. UNIT troops armed with a laser weapon were unsuccessful at combating it. It mentally controlled Chase, and turned the local plant-life against his men, including Scorby who was drowned by pond weeds whilst trying to flee. The Krynoid began to swamp Chase's mansion, destroying it. The Doctor realised that it was about to produce thousands of seed pods of its own.

UNIT called on the RAF who bombed the creature, blowing it up before it could germinate.

Played by: John Gleeson (Winlett), Mark Jones (Keeler), Keith Ashley and Ronald Gough (adult Krynoid). Appearances: The Seeds of Doom (1976).

• A plant-obsessed millionaire growing a carnivorous alien plant life-form at his country estate after falling under its mental control - the plant creature able to turn local flora against humans and animals. An eccentric hero and his female companion trapped in the house as they battle the threat... Not The Seeds of Doom, but "The Man Eater of Surrey Green" - a 1965 episode of The Avengers. Likewise, a hostile plant-based alien running amok at a polar base is also the rough outline of the original 1951 film version of The Thing (From Another World).
• The humanoid Krynoid costume worn by Gleeson was an old Axon Monster costume repainted green. Keith Ashley also wore it on location at Athelhampton House, which doubled for Chase's mansion, though it never actually featured in these scenes in the programme. It was for publicity photographs only.
• Mark Jones also voiced the adult Krynoid.
• Gleeson had earlier played a Thal in the final part of Genesis of the Daleks.
• Keith Ashley was a regular extra and monster performer. Earlier in this season he had been one of the Zygons, as well as the android man who tries to grab Sarah when she approaches one of the capsules in The Android Invasion.