vascular bundles harden
to a back yard pin oak
strung with plastic seed tubes
hung for song birds
who skirmish as if here
is all possible grain
a dendrochronologist may
one day pinpoint cavitation
among its cellulose vessels
our daughter does not know
a tracheid, once cavitated,
cannot return to service
so for now
past rain pools in huddled leaves
like mirror shards fallen
from split denim pockets
as she creaks thick-twined rope
innocent of cavitation
throat vulnerable to the sky