Now a gavotte, perform sedately

I pass these two Norfolk Island Pines almost every day, as I walk to the village or lookout. I'm intrigued by the way they seem to sway towards and away from each other, as though they are performing a stately dance. 

I've often thought of blipping them, but wanted to say something more than what I've just said and couldn't work out what that was. Then, yesterday, jensphotos blipped 'A wandering minstrel' and quoted lyrics by Gilbert and Sullivan. 

My dancing pines suddenly morphed into Marco and Guiseppe from The Gondoliers, who are having dancing lessons:

Now a gavotte perform sedately —
Offer your hand with conscious pride;
Take an attitude not too stately,
Still sufficiently dignified.