Trellis \Trel"lis\, n. [OE. relis, F. treillis, fr. treille vine arbor, fr. L. tricla, triclea, triclia, a bower, arbor, summer house.] A structure or frame of crossbarred work, or latticework, used for various purposes, as for screens or for supporting plants.
To decorate a trellis under which the wedding procession would pass, she bought stock in cream and white.
As you can see it looks quite magical - trellis is a speciality of his and he has used it here to give definition to the space as well as support for the climbers.