during my younger years I saw an English spoken tv serie that aired in Europe around the 90’s-2000’s at the same time that the serie earth final conflict aired (only the first season aired and we never saw the sequels after that).

with the following scene:
– on a planet a man/woman was infected by something and he started walking for a very long time. while most infected people died (s)he reaches his/here distination at the end of this episode and a kind of pollen release from his mounth inside a kind of tunnel. those spores needed to get inside the tunnel to pollinate and then all kind of vegetation emerges.