This is certainly one of the lamer killer plants I can remember, although, hey, killer plant. Even Tarzan can’t free himself, so in a cool Tarzan-y scene, he calls his elephant compadres to come pull him free with their trunks.
Now that would have been a cool end to Navy vs. the Night Monsters.
As I noted in my brief review of the movie, they included this scene in the poster (although not, oddly, the dinosaurs or giant spider), but Tarzan just looks constipated, certainly not in mortal peril.