Recs if you like Hothouse...

Fiction books featuring plants as a major theme. For the purpose of this list, fungi are honorary plants! All fiction genres here (though I am primarily a fantasy reader, so suggestions most welcome!)

Books featuring spores, molds, and fungi. Suggestions welcome.

books where mycology takes over in horrific/fantastical ways

I love mushroom-related horror, and these are all the books I have found that use spores, fungus, or mushrooms as the antithesis of the book's horror.

Science fiction books in english published between 1960 and 1969 (going by when it was published as a book, generally).