Vampires in the meadow

Key to life on Earth, plants are full of surprises, as new BBC series Green Planet reminds us. Amanda Tuke visits a peaceful wildflower meadow and finds that here, among the swaying grasses, something sinister lurks...

- Amanda Tuke

The whisper of a breeze ripples across long grasses and gold-centered oxeye daisies. Marbled-white butterflies loop over the meadow, through air thick with bees and hoverflies gorging on nectar-rich scabious. A kestrel flaps languidly along the hedge to take refuge from the midday heat in an oak tree.

Among the nodding grasses, I can see elegant spikes of chrome-yellow flowers, with petals emerging from pale green pouches that deflate satisfyingly between finger and thumb. This is yellow rattle and, despite those attractive flowers, it is hiding a sinister secret.

On the surface, chalk grassland like this one at Saltbox Hill, near Bromley in Kent, epitomises natural harmony. But dig below that surface and it's a battleground. Every plant here is fighting for its share of light, water and nutrients. It sounds counter-intuitive, perhaps, but meadows like this one are flower-rich because nutrients such as nitrogen and phosphorus are in short supply. This means nutrient-hungry grasses can't dominate.

Yellow rattle, like some other plants, has evolved an ingenious way of thriving. Below my feet, its roots have tapped into the roots of grasses - and it is busy stealing from them. And yellow rattle is not the only parasite here. When I kneel down and part the grass stems, I find downy spikes of red bartsia and prettily veined flowers of eyebright - both parasites, too.

NUTRIENT THIEVES

Parasitic plants make up around 1% of all plant species. Many, like these meadow plants, are partial- or hemiparasites; this means they still photosynthesise to make sugar, but tap into the roots of their host to take water and nutrients. Essentially, they are piggy-backing on the investment their hosts have made in growing an extensive root system.