The thought of hosting Charlie is putting me off my nutrients. Robert can’t help but notice. He doesn’t understand waste.

   I try to explain sleepovers. “Imagine it’s dark and a badger comes bumbling into your root space, digging and snuffling about amongst your things.”

   Things? What things?

   Robert might not have a bedroom, but he does have a secret network running underground. He wouldn’t want that disturbing. “Upheaval, Robert. A mini earthquake in your mycorrhizal fungi.”

   There’s a tremor in his trunk. I’m sure of it.

   I shall attend this sleepover.

   “How?”

   A leaf floats down and bounces off my nose. I catch it and examine it. It looks vibrant. I run my finger along the edge of each lobe and down the stem.

   That tickles.

   “Really? You can feel that?”

   Can’t you?

   I do feel strange, like I’m holding a secret. A key to another of Robert’s mysterious networks. I place the leaf in my lunchbox ready to carry home. It should be comfortable on an uneaten sandwich.