This 1965 novelette has held up remarkably well to the test of time.
Earth has been ‘seeded' with mysterious spores from space. Everywhere, giant alien plants are growing, resistant to every herbicide that research labs and governments have been able to produce. Destroying ecodiversity and crowding out every native species, the plants seem to have no nutritional value to humans or animals. Without farmland, massive famine results. The cities, dependent on farms for food, are first to collapse.
The last pockets of civilization may be farm villages...
In one such Minnesota village, a farmer rules his family and the survivors from his village as a dictatorial patriarch... harsh, but with survival at heart. But he is old, and in ill-health, and times are hard and getting harder. As the characters vie with each other over power and relationships, we see that even desperation is not enough to overcome human pettiness and just plain stupidity.
There's definitely some Biblical allusions going on... although the patriarch is also a religious leader, we see his ‘flock' violate pretty much every one of the Ten Commandments, and commit pretty much every one of the Seven Deadly Sins. They believe they may be being punished by God – but the reality is that humanity itself may be simply beneath the notice of who- or what-ever has caused this destruction.
Very bleak – very, very bleak. But also quite witty and entertaining