Parsonia is a genus of around 100 species of mostly woody climbers with opposite leaves and small whitish flower that emerge in early summer. Most species are originally from Australia and New Zealand and are suitable for a cool greenhouse.
P.capsularis is a slender evergreen climber with narrow 3 inch leaves and small white bell-shaped flowers.
P.heterophylla (common name New Zealand Maori jasmine), below, is another slender evergreen climber but has fragrant creamy-white flowers.
The growth may be trained around canes in a pot or planted out and trained up the inside of the greenhouse.