I wonder, did it ever have a tune as such? For sure I used to sing it to a sort of melody-cum-psalm-tone accompanying myself on a medieval harp, circa 1983. But before that, circa 1980-81, you could catch the author of the piece performing it with West Northumberland's once-premier, much missed & fondly remembered, alt-folk combo Badger in the Bag (the Incredible String Band meets The Grumbleweeds with a healthy dose of Malicorne - & featuring the multi-instrumental talents of Whapweasel's Mike Coleman no less...) as part of their Green Man's Morris sequence.

Here it is in full:

^^
The Green Man's Song - by 'Dancing' Jim Wetherspoon   

Before you laid your tracks or daubed your houses;
or the drove the furrow hard across the wold,
I danced alone beneath the spreading branches,
and sang away the winter's clinging cold;
spelling sap to rise and the buds to quicken,
and lithe green shoots to spring from out the mould.

Wry masons and woodcarvers called me to them,
when spires were raised to match my tallest trees;
they set my leaf-mask leer on arch and lintel,
and grinning out from between the pimply knees,
of dozing friars, on bum-worn misericords
to mock the preacher's dry solemnities.

But I'll fetch home the summer from the green-wood;
the trees & flowers unfolding to my song;
leaf-canopied; ablaze with twisting ribbons;
I'll call from hearth and plough the merry throng.
And on the winding green, with pipe and tabor,
I'll lead you all a fine dance, the summer long...