Weeds: How Vagabond Plants Gatecrashed Civilisation and Changed the Way We Think About Nature

  • Richard Mabey
Profile Books: 2010. 288 pp. £15.99 9781846680762 | ISBN: 978-1-8466-8076-2

Like humans, weeds are pervasive, domineering and badly behaved. But they adopt these traits only in order to reproduce. As naturalist Richard Mabey explains in Weeds, they are an in-your-face example of evolution by natural selection: weeding benefits weeds by allowing those that evade the hoe to produce seeds that inherit the very characteristics that allowed escape; using herbicide causes weeds to become more resistant to such poisons.

Mabey weaves social history, psychology, literature and art into his clear rendering of plant biology. Explanations of evolution sit alongside explorations of flower symbolism in Shakespeare. This blend, familiar to fans of his earlier reflections on nature in the wild, broadens the book's scope to human attitudes to plants in general.

Indeed, the concept of a weed makes sense only in relation to people — they are plants that cause us trouble by growing where we don't want them. Most of the social connotations of weeds are negative: unruly, weak or aggressive. Yet these designations are fluid. Some plants, such as St John's wort (Hypericum perforatum) or hemp (Cannabis sativa), have passed from love to hate and back again. Others, such as autumn ladies' tresses (Spiranthes spiralis), are a rampant but admired invader of our lawns.

Some weeds considered ubiquitous today were once rare: rosebay willowherb (Epilobium angustifolium), depicted among the fine flora on the ceiling of the Natural History Museum in London, was described by some nineteenth-century botanists as a woodland plant 'not often met with in the wild state'. This magenta-flowered perennial carpeted the bombed areas of 1940s London, earning it the common name of fireweed. Its tiny seeds, carried on downy plumes, were dispersed by turbulence along railways; it now colonizes cities across Europe and North America. It is a good example of how weeds are a human construct, promoted by our tendency to disturb land.

Naturally invasive or easily transported species are also troublesome, particularly on islands with rare flora such as Hawaii, the Galapagos and Australia. For example, the velvet tree (Miconia calvescens) has taken over rainforest areas in Tahiti and is spreading on Hawaii; it chokes off native vegetation, preventing natural forest regeneration in these fragile habitats. But these plants arrived with people. Homo sapiens is the ultimate invasive species — coming out of Africa to colonize the globe, altering the planet beyond recognition.

Weeds highlights our ambivalence about naturalness and artificiality. We often think of pristine nature as the landscape we, or our grandparents, grew up with. Yet nature changes all the time. In the Pleistocene, much of northern Europe was covered with ice: no plants grew. Our entire flora is invasive, but that hasn't stopped us loving it.