Willow branches are extremely flexible and can be woven into tight structures that get less brittle than other wood over time. Willows are among the trees first used by humans in the Northern hemisphere. The world's oldest fishing net, dating back to 8300 BCE, is 90 feet (27.4 meters) of woven willow fiber.
Patrick Dougherty - stickwork.net
Since the 80's Doughterty has been creating these large scale environmental works all over the world. He imports saplings by the truckloads and directs teams of volunteers to install them.
He said this about one of his most recent pieces Daydreams- the house that is consumed by the willow sculpture -
Daydreams is built in and on a replica of a prairie schoolhouse. This schoolhouse was built new to look old and to provide the backdrop for the sculpture. The work, composed of five interior and two connecting exterior elements, is entitled Daydreams for all the dreams of the wild that sustain children as they endure the whine of imparted knowledge.
He installs them at museums and parks fairly frequently in North America. If you get a chance to see one, or volunteer to work on one, you should definitely go.
Marco Casagrande - casagrandelaboratory.com
Sandworm, built in 2012 is a shelter made entirely of willow. Part of a Belgian beach it is 45 meters long and 10 meters high.
Casagrande calls it weak architecture. Not weak in material, but weak in the sense that it is "architecture that wishes, wants, to become part of nature and sets out to do this through flexibility and organic presence."