Captain journals science team as they eat plants on alien planet

[Von]

A science team accidentally lands on a new planet that is covered with plants. Possibly marooned there? They eventually start to eat the plants and the side effect is that they begin to lose their intelligence. This is told in the form of dairy entries by the captain of the group. He eventually succumbs after eating the plants; his last journal entry is made up of non-sense characters like curliques, etc.

1960s-1980s?

 

[PaulMmn]

Did they turn into some of the alien creatures? Cow-like, with beehives embedded in their sides. They walk into the Earther's camp and conveniently fall dead just when their food is running out...

 

[Von]

Did they turn into some of the alien creatures? Cow-like, with beehives embedded in their sides. They walk into the Earther's camp and conveniently fall dead just when their food is running out...

No, I think the people stayed in their own form but just lost their capacity to think.