Name That Trauma :: Reader Chris F. on Plant People

I don't know the name of the movie…..I've been trying to find it for years….it was on T.V. (HBO?) Early '80s and a group of people were stranded on an island (maybe a planet) where the only source of food were plants that when you ate them, you would turn into a plant and one by one the people would give into hunger and eat the plant. It is the only movie that has ever creeped me out and it still does to this day. Any idea what the movie is?

UNK SEZ: Chris F., I've come across many a killer plant movie in my day but few where people are transformed into the plants that they've eaten. The only one I can think of where that scenario occurs is MATANGO (1963) a.k.a. ATTACK OF THE MUSHROOM PEOPLE, Directed by ISHIRO HONDA (GODZILLA) and based on the story "The Voice In The Night" by WILLIAM HOPE HODGSON. It just might be the one you're looking for.

In the movie a group of shipwrecked people find themselves on a bizarre looking deserted island, so strange it could be mistaken for another planet. Although warned not to eat the fungus found on the island, starvation gets the better of them. One by one they succumb to temptation, only to go mad and turn into plants themselves.

As wacked out as the premise sounds, the trippy local and the palpable fear of contagion really are disturbing. Who would ever think that a movie about killer mushrooms could be so effective? Now, I'm not sure if this is the one you're seeking, I doubt it was ever on HBO but even if it's not, hopefully I lead you toward a horror classic you will enjoy anyway. Otherwise the floor is open, does anyone know of a movie that might better fit Chris F.'s description?

UPDATE: Unk was right.