Every question holds its answer, like every answer holds its question, bound so close that they travel together like the wings on either side of a seed.

We were flying along in the car and we saw a tree off to the side. Isn’t the Scots pine the loneliest tree in the world? I said. Look at it, look at that one there, standing so mournful, and apart, and dour, and elegiac. Scottish to its roots.

Uh huh, you said. If you say so.

Look at it, I said. So noble and solitary. And it’s all that remains of a huge ancient Caledonian forest. It’s so romantic.Except that as a species, you said, it also happens to be thriving all over the place, from Sutherland to Surrey, Lapland to southern Spain, Glen Affric all the way across to the forests of eastern Siberia, a Scottish-to-its-roots tree whose roots, by the way, happen to be very versatile, can develop to taproot-depth or survive on really shallow ground.Eh, I said.Then I didn’t say anything.Then I said: Like it’s been sculpted into aloneness by the wind.Well, aloneness, yes, you said. But that little yellow-green bird is in love with it.What bird? I said.

Female Scottish crossbill, you said. And the male Scottish crossbill, which is redder in colour, is also in love with it. All the Scottish crossbills are. Don’t be pining for the lonesome pine.

I didn’t see any bird, I said.

Their crossed-over beaks are particularly good for getting the seeds out of Scots pine cones, you said.

You’re making this up, I said.

No, they’re real, you said, though till recently they were so under threat that they almost stopped being real. They look like little Scottish parrots, imagine a little parrot the size of a sparrow. And without specific Scots pine cones to eat, these birds – unique to the UK, the only birds which never migrate, picky little birds whose whole diet is Scots pine cones – would be history by now.

You’re looking all this up on your phone, I said.

You held your hands out in front of you in the dusk light in the car to show me there was no phone in them.

How do you know all this stuff ? I said.

Same as you know all the noble solitary lonely elegiac stuff, you said, about that tree being a sign of lone buried warriors at lonely crossroads, deeply symbolic of the terrible solitariness of all things.

Well – I said.

Inhabited, you interrupted, not just by the Scottish crossbills, but by all sorts of birds from siskins all the way to eagles, and by red squirrels, by wood ants and their aphids, and by a particular kind of moth which loves pine, and many other life forms including two hundred different fungi.

I didn’t know you knew any of this, I said. I didn’t know you even knew there were two hundred different kinds of fungi –

Beautiful, you were saying, with the terrible pining beauty of abandonment, uh huh, and all the years of its wood being made into ships and boats, because having so much resin in it, it tends not to rot when it’s wet as quickly as other wood does, and all the years of its tall straight trunk being so good for masts and pitprops and telegraph poles and fencing and being made into furniture and made into paper, and all the years of its resin d’être.

Its what? I said.

Resin, you said, the reason turpentine got made, which meant artists could clean their brushes and hands and house painters need not blame their tools; good, too, for helping violin bows glide across strings for centuries, and there’s also all the years of its needles boiled and inhaled helping clear blocked chests, helping fight infection, even helping restore confidence, the Druids thought, to people who have come to dislike or disparage themselves.

Yeah, but you’re not even Scottish, I said.

Your solitary lone traveller, you said, your Scots pine.We were well past the tree now, into a treeless Highland landscape. It was already a couple of miles back, that tree. Dark was falling.

And that’s how you tell what kind of tree it is, you said. The mature trees have quite bright-coloured trunks.

Actually that’s not how you tell a Scots pine, I said.

Yes it is, you said.

There’s something I know about that tree that you clearly don’t, I said.

There’s nothing I don’t know about that tree, you said.

So because I was half annoyed and half impressed, rather than say it out loud there in the car I thought it inside my head, about learning when I was small at school how you tell a Scots pine from other pines, and the way you do this is to look at the needles, because a Scots pine always grows its needles in twos together in a single sheath, never one by itself, always two, so that there are pairs of needles on every branch, countless thousands of pairs of needles on every single tree.

Come on, what? you said.

Well, how it nearly died out, I said instead. Like your birds did, the species I mean. After years of being cleared for sheep, cows, cut down and used for building.

I didn’t know if this was true, but it sounded good.

But it came back, you said next to me. And it still has the ancient forest deep in its design.

I thought of the two needles, green tinged with blue, tight-bound together at one end, and I could almost smell the smell of the tree. I thought how the needles in their little sheath were like the image in a poem I only half-remembered, where two lovers are held together in the world like the points on a pair of compasses, hinged at the heart and always pushing apart.

Solitary, you said. Romantic. Alone and lonely. One tree against the world.

We drove on. Miles behind us in the landscape the tree stood evergreen in the winter and the dark and its trunk, being the trunk of a mature tree, was, yes, regardless, bright.