To vegetate is an odd verb, sometimes even an unpleasant one. But Richard Mabey’s great book is positively fuelled by the curious green energy of its contradictory meanings. To vegetate: to grow and cover the ground, but also to be apparently inactive. The word grafts with its opposite and cleaves to plant life. Take the potato, for example, and the couch potato: the vegetable world is the permanently growing skin of the earth, but it also seems to be just there, covering almost everything but doing almost nothing.

The Cabaret of Plants: Botany and the Imagination performs around this paradox, exploring its tensions, revelling in its surprises, and urging us to bin any notion we might have of plant life being somehow passive or a static backdrop for the more go-getting life of our planet. Plants, Mabey believes, are more than simply attractive or useful, having “strange existences and unquantifiable powers”, which lend them “alternative solutions to living”. It is not ridiculous, although he says he is “embarrassed” to think of them as having “selves”.

In its imaginatively bold and scientifically risky way, Cabaret is the summation of a lifetime of looking at plants and reflecting on them. For more than 40 years Mabey has been writing up what he has seen and understood of the flowering world. His many books and hundreds of articles amount to a masterly series of benign emissions from the greenhouse that is our planet. In 1972, Food for Free taught us to forage. It is still in print and is, Mabey has said, his pension. Marsh samphire gets special attention in that book: it’s his favourite wild food, and the salty asparagus has a delicious but challenging reprise in the new work (as a plant bent on creating terrain where it cannot thrive).

In 1980 came The Flowering of Britain, a collaboration with the photographer Tony Evans (who also gets a fascinating turn in Cabaret that will be a comfort if you’ve ever struggled to take a photograph of an orchid on a windy hillside). Flora Britannica followed in 1996, a magnificent collection of words husbanded by Mabey from across the country that amply demonstrated the continuing presence and potency of wild flowers in the British imagination, even at a time of species loss, habitat degradation, and the increasingly common human retreat to lives spent indoors. A personal crisis precipitated a breakdown a few years later, and a cruel hiatus when nature – plant life above all – ceased to sustain Mabey as it had previously. He emerged again, thanks in part to rediscovering his plant love, with Nature Cure (2005), his most moving and personal book. Beechcombings (2007) brilliantly corrected the way many of us think of trees as needing our help; and Weeds (2010) asserted the resilience and vitality of those derided plants we have called out of order but that are simply making their best way in a world increasingly fashioned by us.

All these vegetative shoots entwine in the great-rooted blossomer that is The Cabaret of Plants. The book reads as a happy tangle of beautiful stories and studies from a career that has stepped between science and poetry, or as its subtitle says, between botany and the imagination. Mabey is a professional writer and has never been other than an amateur botanist. But his amateurishness, as written, has always revealed the roots of the word: to be an amateur is to be a lover, and this is the book of a man in love with both the known facts of plants and the dreams they sponsor, a man who has a microscope at home and is eager to penetrate the mysteries of vegetal life, but who is just as likely to marvel or swoon at what he finds, and wish for such softer responses to be admitted as legitimate, so to keep (in Coleridge’s phrase) the heart alive in the head.

That is flower power, and that is this book’s concern. Mabey has little to say here about our national green-fingered obsession, our capture and fixing of the wild in our lawns, flower beds and allotments. Instead, he gardens with his imagination and by eavesdropping on others’ thoughts and fantasies of plants across thousands of years. His flowers are energetic, unpredictable, resourceful and transgressive. They are, above all, survivors. Of all ecological and conservation-minded writers, Mabey is among the most optimistic. Indeed, he sees a kind of hubris even in the diagnosis of the anthropocene. Plants will outlive all of us. The poet Edward, Lord Herbert, wrote in 1620 of a “self-renewing vegetable bliss”. Some people have understood this, a mongrel crew of poets and naturalists, explorers and obsessives, but most of us have not. The job of the book is to wake us up by welcoming us to the club: a cabaret with a master of vegetable ceremonies.

Mabey is briefly troubled by the lack of representations of flowers in the earliest human art (cave paintings being more fixated on big mammals), but he finds enough to cheer him and after that doesn’t look back. Chapter after chapter does plant after plant: phallic orchids, ferns as clothes, giant water-lilies, a vegetable lamb, intelligent mimosas and many more. There are several floral rhapsodies from the Victorian age, the era on the cusp of the two-cultures rift and troubled by the organising revolutions of Linnaeus and Darwin. A thicket of poets “ensnared” (as Andrew Marvell put it) by flowers gets original treatment too. Keats’s flora is brilliantly pressed.

The “arcane power of plants”, as the poet-gardener Sarah Maguire has said, has not been “unsettled” by science. Mabey is especially good when writing about trees and flowers he has seen himself, but one other story in Cabaret might define the book and is so beautifully told it is worth the whole. Through the 1970s and 1980s, the English artist Margaret Mee hunted through Amazonia in order to paint a blooming moonflower. The plant is an epiphytic cactus that flowers fleetingly in the dark with sweetly perfumed large white “frilled and starry” blooms. Mee caught in flagrante a single flower and painted it (her picture is included) and it is difficult not to weep reading about the hard-won but exquisite meeting of art and nature, poetry and fact, observer and observed, one Margaret and one moonflower.

I have had the privilege and pleasure of botanising with Richard Mabey. And after this book we all might. He moves slowly but with great intensity as if somehow dowsing the green fuse itself. Eyes down, he walks with a soodling gait and a mazy motion (like John Clare or Coleridge, two of his hero poet-botanists). He is not King Lear, fantastically adorned with flowers and dipping in and out of madness, nor Falstaff, playing with an imagined meadow at his fingertips on his deathbed, but he has some qualities of both of those giants of nature. We are lucky to have him. He has changed the way we are with plants and made a loved world lovelier still.

Tim Dee is a writer and BBC radio producer. He is at work on a book following the spring through Europe

• The Cabaret of Plants is published by Profile (£20). Click here to order a copy for £16