Marc triggered this one.
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The Green Surge
Nature’s surging hydraulics lay dormant,
thickened and stilled by Winter,
sheltered in deep roots.
But come Spring, as the soil warms,
they move again.
Irresistible. So much green vigour,
plants and trees have to bloom,
an abundance of foliage and flowers.
Otherwise they’d burst,
like a child hungry to share his news.
Wow, what an image. Beautiful Gyppo. Also:
Just nice stuff.
Cheers, Marc.
Physics into poetry 
Liquids are incompressible. This is the basics behind man-made hydraulic systems. If that warming/resting sap surged back up without the outlet of unfolding leaves and flowers, to replace the ones which died and fell away, the stems and trunks would crack and split.
I once cut a dangerous, (window threatening), branch from a birch tree at the wrong time of year. It was about four inches thick, so that was a lot of cut surface, and it ‘bled’ sticky sap copiously for about three weeks before the cut sealed itself over.
Things like this have fascinated me since childhood. There is indeed ‘a time for every purpose’.
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A very readable poem. The finishing metaphor is adroitly done.