Several epochs after the age of Men, Earth bristled with flora. Each continent a forest stretching from sea to shining sea. The scorch marks left from when we were burned from its surface covered by a verdant floor of grasses and lichens, moss wrapped 'round the skeletal, teetering remains of buildings long collapsed, their foundations, once solid now soft as loam, as fertile a fertilizer as peat in a bog.
Earth's masters now were the trees.
Unfettered growth for tens of thousands of years left them towering high above the few creatures that remain, skulking in the darkness, eking out invertebrate existences down in the detritus, a layer of debris dozens of feet deep. The stuff of potent life, borne on the bodies of those long gone: intelligent upright creatures and the poor Animalia kingdom they conquered and ultimately dragged into extinction's depths with them. Still their dreams were remembered, perhaps something of what the trees absorbed through their roots recalled their yearning. The oil compressed from the rotten flesh of man boosted them through the mesosphere and towards the black.
Some day, some day… their sap-slow thoughts conjured an image of stars, and the home their branches might make among them. Warmed by symbiosis with the formerly living's brackish blood they reclaimed, they climbed… and climbed toward the absolute cold. Somehow they knew, to the extent their brainless selves could know, the millions of years long journey would be well worth the cold. That somewhere out there was life worth seeking. That the sacrifice of men, once their masters, now merely fuel, would not have been in vain.
They would find those creatures of flame, borne to Earth in pestilent ships of hide and pus. Whether they would thank them or destroy them in kind they knew not. The silent whispering of Man's ghost, the birthplace of all violent ideas, slumbered still deep in their timbers.