What I remember is that there was a space station or ship that had an infected crew member. Either it landed on earth or it crashed, and it released the spore for the alien plant. Government agents, a man and a woman, went out to investigate the field where the alien plants had sprouted up all over the place. They looked sorta like silk lilies. They would scream and shoot what looked like Kix cereal out of the center. I don’t remember if this was to poison/infect people or just how the plant reproduced. All I remember is that the woman and man were in the field talking about how it was spreading while a plant would go off around them every so often.
It’s an old film, looks like a technicolor movie with similar set design and atmosphere to ‘5 Million Years to Earth’.