And there I was, for all those years, wondering why the word "rowan" in Marie's Wedding always had no capitalisation. Guest, 'twas merely a jest.

But now you mention it.....
The mountain ash (Sorbus aucuparia, I believe) that the Scots call a rowan tree is also the second tree in the Irish tree alphabet, known for its association with stone circles all over northern Europe, its ability to divine water and precious metals, the notion that only a whip made from rowan can control a bolting horse and various other things that Robert Graves pulled out of Celtic lore.

By comparison, the tree that is called mountain ash in Oz (Eucalyptus regnans) has no particular associations with any of the above but was (until they cut it down to measure it as 366' long) the tallest tree in the world; its mates are now only the tallest flowering plants in the world and the sequoia is regarded as the tallest tree. I have had the privilege of climbing a mountain ash (the Oz version), where the lowest branch was about 120' above the ground and about 40' above any of the understory. Beautiful salmon grey trunks for the whole 360 degrees around and all turning salmon pinks in the setting sun as I returned to earth.

Cheers, Rowan (whose lips are reddish)