Riddle

The tree whereon decay All those from mortals sprung,— Full old, and yet whose spray Is ever green and young; To catch the light, it rolls Each leaf upon one side; The other, black as coals, The sun has ne'er descried.

It places on new rings As often as it blows; The age, too, of all things To mortal gaze it shows. Upon its bark so green A name oft meets the eye, Yet 'tis no longer seen, When it grows old and dry. This tree—what can it mean? I wait for thy reply.