*Idea for a short story*
A botanist studying the development of epicalyx (an external part of a flower) happens to share his work with his neighbour, a cryptographer, who becomes convinced that there is a pattern to the variation in the shapes. They realise that all the plants in the botanist's garden are developing their epicalyx in the same variations and the cryptographer begins to suspect that it means something. At the same time a colleague of the botanist has noticed a build up in bacteria that produce sulphur as a by product of photosynthesis instead of oxygen. They realise that the vegetable world has attained consciousness and the plants are sending them a message, an ultimatum that they will stop producing oxygen if humanity does not mend its ways.