2. Plants are amazing: they provide food, air, medicine, and material with which we can create buildings, furniture, and art. But through an ancient yet obscure craft, still-living plants can themselves be turned into bridges, tables, ladders, chairs, works of art, and even buildings. Known variously as botanical architecture, tree sculpture, tree-shaping, tree-grafting, pooktre, arborsculpture, and arbortecture, the craft is, at its essence, construction with living plants.

3. The concept seems to date back to prehistoric times. Perhaps the oldest examples are the living bridges of Cherrapunjee, India. 1. Root Bridges of India In the depths of northeastern India, in one of the wettest places on earth, bridges aren't built ---they’re grown!

6. Grown from the roots of a rubber tree, the Khasis of Cherapunjee use betel nut trunks, sliced down the middle and hollowed out, to create "root-guidance systems." When they reach the other side of the river, they're allowed to take root in the soil. Given enough time, a sturdy, living bridge is produced.

7. The root bridges, some of which are over a hundred feet long, take ten to fifteen years to become fully functional, but they're extraordinarily strong. Some can support the weight of 50 or more people at once. One of the most unique root structures of Cherrapunjee is known as the "Umshiang Double-Decker Root Bridge." It consists of two bridges stacked one over the other!

10. Because the bridges are alive and still growing, they actually gain strength over time, and some of the ancient root bridges used daily by the people of the villages around Cherrapunjee may be well over 500 years old.

11. But these are not the only bridges built from growing plants. Japan too, has its own form of living bridges. 2. The Vine Bridges of Iya Valley

12. One of Japan's three "hidden" valleys, West Iya is home to the kind of misty gorges, clear rivers, and thatch-roofed houses that one imagines in the Japan of centuries ago. To get across the Iya River that runs through the rough valley terrain, bandits, warriors and refugees created a very special, if unsteady, type of bridge made of vines.

13. This is a picture from the 1880s of one of the original vine bridges.

14. First, two Wisteria vines -- one of the strongest vines known -- were grown to extraordinary lengths from either side of the river. Once the vines had reached a sufficient length they were woven together with planking.

15. The bridge had no sides, and a Japanese historical source relates that the original vine bridges were so unstable, that when those attempting to cross them for the first time would often freeze in place, unable to go any farther.

16. Three such vine bridges remain in Iya Valley. While some (though apparently not all) of the bridges have been reinforced with wire and side rails, they are still harrowing to cross. More than 140-feet long, with planks set six to eight inches apart, and a drop of four and a half stories down to the water, they are not for acrophobes.

17. Some people believe that these existing vine bridges were first built in the 12th century, which would make them some of the oldest known pieces of living architecture in the world. But there is one group of ancient peoples who took living architecture to an entirely new level.

18. "Espalier" Art FormAnother more common form of ancient tree shaping is known as espalier. Espalier is the process of making two-dimensional forms out of trees. A popular practice in Medieval times, the craft likely dates back to ancient Egypt. Espalier can be used to make ornamental trees, increase the yield of a fruit tree, or build a fence or wall from growing trees. On Pacific Street in Pacific Heights, San Francisco:

21. The Auerworld Palace Many of these marvels are the works of one dedicated person, but the mysterious Auerworld Palace took some 300 volunteers to create. Architect Marcel Kalberer and his group, SanfteStrukturen, are re-envisioning the way living building materials and techniques can be used to design modern spaces - with willows.

25. Constructed in 1998, the Auerworld Palace in Aeurstedt, Germany may be the first modern "willow palace," but the techniques Kalberer uses are ancient. Sumerian reed houses were famous for their construction of tightly bound reeds.

28. Waldspirale, or Forest Spiral A German apartment building hosting as many trees as human occupants.

29. The Austrian artist and architect FriedensreichHundertwasser is said to have once called straight lines "the devil's tools." His famous apartment building, Waldspirale, is a testament to his hatred of straight lines and his love of nature. Located in Darmstadt, Germany, Waldspirale translates to "wooded spiral," and that is exactly what it is. It hosts as many trees as human occupants.

30. Quigley's Castle. If you look at the large windows in the centre of the house it looks like they are reflecting trees on the outside. Those are actually trees inside the house!

31. Tree grafters Peter Cook and his wife Becky Northey, have developed their own special tree-shaping techniques, which they call pooktre

32. Vine railing for staircase

33. Trinity December 2009