Nurserymen tell us trees
grown under glass
in the calm of a greenhouse
          are spindlier, their trunks
          more modest, more inclined
          to bend under the burdens
of new branches and leaves,
their ordinarily haphazard
outgrowth unbalanced
          in the direction of sunlight
          exclusively, taking no part
          in the play of weather
outside the windows. Inside,
trees that have grown accustomed
to constant temperature
          and easygoing air
          become much less sturdy
          than wild ones subjected
to sudden changes, surprises
of much too much, too little
or too late. Yet their caretakers
          behind glass have discovered
          if they hold the privileged ones
          in hand and shake them,
shake them, even pound them
with padded mallets, they straighten,
stiffen, and grow tall.