Complex sentence: The Red Weed is not mentioned at all in the radio adaptation, and is absent from the 1953 film; however in a retcon established for the TV series follow-up, the aliens originate from Mor-Tax, which is a garden planet.
Split into simpler sentences: The Red Weed is not mentioned at all in the radio adaptation. It is also absent from the 1953 film; however in a retcon established for the TV series follow-up, the aliens originate from Mor-Tax, which is a garden planet.