The Sunflower blossom tracks with the sun, its petals reflect sunlight to a central bulb where photosynthesis takes place. They also have a limited ability to sense creatures nearby and will alter the focus of the petals to burn intruders to the sunflower patch. The image on the right shows a sunflower that is inconsistant with novelizations, depicting a center blossom highly reflective surface that can burst at a target the light stored in fatal beams.
The Tnuctipin secretly engineered the Sunflowers to turn on their Thrintun masters, as part of a multi-stage plan which also included the Bandersnatchi, whose aim was to completely destroy the Thrintun. The revolt proved mostly successful in that the Thrintun were obliterated, except for a handful of beings who happened to be encased within stasis fields. Unfortunately, the Thrintun were able to send out a suicide message across the stars, effectively obliterating all life in the galaxy. It would take billions of years for sentient life to evolve again as a result of this catastrophe.