Restrictive Relative Clause

Planted when we moved here, it evolved
into spring's welcome from the narrow road
when I came cycling home, its branches stiff
with blossoms, a pink signal in the sun,

reminder of those early days, its straight,
firm branches slanting upwards past the eaves,
across the dull brown tiles and in the hall
we switched the lamp on when the post had come

as light came filtered through the thick green leaves
and we swam from the kitchen to the dim
cold living-room, until at last it grew
too dark, and, branch by branch, we took away

spring's joy, purveyor of the instance I
so often used to demonstrate my class
the difference some commas will show them: trees
which grow in front of your window ruin your view.