I probably wouldn't have noticed the supermarket delivery van that morning, if it hadn't have blocked Belinda in. It set me thinking, though, and as I cleared up after our coffee-morning I found myself fretting about Mrs Scott. You know how it is with elderly neighbours. You don't see them for days, and you can't help wondering if they're sitting there dead, gradually becoming part of the sofa. A delivery seemed to prove otherwise, though, so I popped round to see her.

She was moving bags from doormat to kitchen, one at a time and painfully slowly. I took over, of course, and then made the tea, and it was only when we sat down that I got a good look at her. She seemed smaller than ever, paler and more white-haired. She was glassy-eyed and pucker-mouthed, like a frozen scream. I shouldn't have come. I'd be having nightmares for weeks.

It was a conversation of sorts, and I learned that someone came into clean, and that they'd fixed the taps so she only had to lean on them, and that she probably lived on grapes. I shouldn't really have asked why she didn't go into a home, but the horror of it all got in the way of my judgement. When I did ask, though, she raised up a pearly, clawed hand and pointed out through the window.

'You mean the tree?' I asked, and she nodded. She began to speak more clearly and deliberately than before, as if something important had woken in her mind. The great walnut in the garden, she said, was her grandmother. When she was very old, the old lady had changed into a tree.

Mrs Scott's grandmother changed over the course of a few days, or it might have been weeks. Her joints stiffened and disappeared, and she became heavy. They couldn't get her in and out of bed any longer, so they propped her in a corner. Her eyes were the last human part of her, but the bark that had once been flesh closed in over them, and she became rigid and wooden. They did the natural thing, of course : they planted her.

The sharpness of Mrs Scott's gaze began to cloud once more. The clarity of her speech dulled too. She waved the claw-hand towards a willow on the opposite side of the lawn. That was her mother, she said, only she no longer seemed so sure.

I washed and dried the teacups pretty quickly, I can tell you. I got out of there as fast as I decently could. The last thing she said, though, stuck right between my shoulder-blades, as I hurried through the front door.

'But who is going to plant me?'