The way the early Christian bishops and missionaries behaved towards plants can make depressing reading. Personally I think there's nothing more magnificent than a great tree, its roots deep in the earth, its branches soaring to the heavens.

And the ancients thought so too. Literary sources tell us how the ancient Greeks and Romans punished anyone damaging a holy Oak. Even the Ostrogoths had a law forbidding anyone from chopping down Oaks and Hazels because they were regarded as trees of peace. But it all changed with the spread of Christianity, and suddenly these trees were going to be prime targets for destruction.

For me, destroying a tree (unless, obviously it's dangerous and about to fall over) makes little sense. Christians believe that their god created everything, so why destroy his creation?

And yet that’s exactly what happened. In Germany, St Boniface smashed up Donar’s sacred oak. In Rome Pope Paschalis II ordered a sacred walnut tree to be chopped down and a church was built on the site. Yet in ancient Rome the walnut was regarded as sacred, only with the coming of Christianity did it become known as a witch tree.

And it wasn't just individual sacred trees that suffered for these frankly loopy ideas. Pear trees were ripped up en masse, and elsewhere Christian missionaries felled what they called ‘god oaks’ to prevent people worshipping them.

Yet in spite of all this axe wielding, people still revered trees. The magical thinking behind this was that trees were so closely associated with both the gods and with mankind, that they could take on people's sickness and disease and effect a cure.

We know from various snippets here and there, pieces of folklore, local traditions, that many trees were used for magical healing well into the nineteenth century and sometimes the twentieth.

That’s almost within living memory. And what that means on a practical level, of course, is that we have a much better chance than you might think of reclaiming this herbal heritage. Yes, it will be corrupted with the passing of the centuries, and sometimes it will feel a bit like trying to read a book through a dirty window pane! But the knowledge is there - and it's up to us to see what we can find.