When we go outside and do a bit of gardening, what are we really doing? All that potting and re-potting, digging and hoeing, forking, composting and sowing – what’s it all for? We enjoy it, of course, especially when the plants flower – and if we plant vegetables, the ground will help to feed us as well. But could something else be going on? Could it be that the whole process isn’t about what we’re getting from the plants but the other way around? Could it be that we are not using the plants but that the plants are using us?

That is one of the intriguing ideas at the heart of The Reason For Flowers, a detailed, passionate and thorough history of flowers and their uses by the ecologist and entomologist Stephen Buchmann. Buchmann explains the science of flowers clearly and engagingly but he also explores and describes their pure, unscientific joy, and in so doing suggests the aesthetics and the science are one and the same – flowers fill an important emotional niche in our lives and, in return, we collect their seeds, sow them and then protect the plants they grow into. Just who has domesticated whom?

Before laying out this theory, Buchmann explains the inner workings of flowers in fascinating, salacious detail. Flowers are, he says, nature’s advertisements, using their beauty to beguile and reward passing insects, birds, bats (or people) willing to attend to their reproduction. Indeed, he often uses what seems like the vocabulary of the pornographer rather than the scientist but it is appropriate: flowers are almost entirely obsessed with sex and reproduction (as are some humans).

“Flowers are, in essence, the sex organs of the plants,” writes Buchmann. “And they need sexual favours to spread their sperm and have their eggs fertilised. The animals that fly from flower to flower, along the way dispersing each flower’s sperm (in the form of pollen) to other flowers, enables plants to go on virtual dates with each other and to reproduce.” It’s a simple exchange: an insect lands on a flower, it feeds on the plant and then carries the pollen to another plant.

As an entomologist, Buchmann is able to explain the fine details of this relationship between plant and insect. The flower/bee exchange for example is one that happens without the bee’s knowledge – if anything, it is the flower that comes off as the intelligent one. For millions of years, plants have been hiding pollen on bees in places where they can’t groom it off, and it remains there until accidentally brushed on to the stigmas of flowers. Clever flower.

There are also some surprising facts in Buchmann’s account of insects and flowers. Flies, for instance, are the second most important pollinators after bees which might help us to overcome our revulsion at them – we assume, when they land on food that they have just been somewhere less pleasant, but perhaps the fact that they are almost as important as bees in the ecological balance of the planet might help us look at them differently.

Buchmann also wants to remind us that, although we may think we are several hundred rungs above insects and flowers, we are, in some ways, exactly the same as flies and bees and that, while we may believe we are in control, a number of scientists believe flowering plants have more control over us than we think. “It’s perhaps not a stretch,” writes Buchmann,” to realise that flowers may target their beauty and charms at us, not just insects, birds or bats. Plants may be seducing us to do their bidding, making us serve their sedentary sex lives.”

It is a fascinating idea – that we are being thoroughly used to promote the lives of flowers and plants – but in explaining it, Buchmann also suggests we are not fulfilling our part of the bargain as well as we should. Flowers and humans depend on each other for mutual survival, but many wildflower species are now threatened with extinction; we need to get our act together and understand, as he says in the title, the reason for flowers. Which, finally, leads him to a question, one that environmental problems such as deforestation make more important with each passing day: if flowers heal us, shouldn’t we also try to heal flowers?