I suppose 'Dear Mr and Mrs Birch' since they have both male and female flowers?

From Melbourne’s email-a-tree service archive:

My dearest Ulmus

While languishing inebriated 'neath your ample verdant canopy I was inspired to verse:

I think that I shall never hear a poem as lovely as a beer. A beer McSorley's had on tap with golden base and snowy cap.

The golden stuff I drink all day until my memory melts away. Poems are made by fools I fear but only [insert] can make a beer.

But you adjudge me MAD.

Best wishes,

Alfred E. Newman