For thousands of years, man has practiced the art of tree and plant shaping.  There are many methods for actively influencing a tree’s growth, such as bonsai, topiary, espalier, pleaching, and grafting.  Some of these methods may be used together to grow a living structure.

Bonsai

Bonsai is the art of the miniature landscape.  The cultivation of plants in containers dates back to ancient Egypt, around 4000 B.C., where pictorial records show plants being grown in containers cut into rock.  “Bonsai,” translated as “tray planting” in Japanese, is believed to have taken hold as an art form sometime between the 3^rd century B.C. and the 8^th century A.D in China, where it is known as “Penjing.”  Bonsai was introduced to Japan around the beginning of the 13^th century.  Using a wide variety of techniques, such as leaf trimming, pruning, grafting, and defoliation, the bonsai artist is able to create miniature landscapes in a myriad of traditional styles.

Topiary

Topiary is the art of sculpture, using living plant material – trees and shrubs, mostly – as the medium.  Ancient writings show that the art of topiary has been practiced for over 2,000 years and dates to the Romans.  The best plants for topiary are evergreen, with small, dense leaves, such as box, myrtle, or yew.

Traditional topiaries have foliage trimmed into geometric shapes such as spheres, cubes, cones, pyramids, and obelisks.  There was a decline in the popularity of the art throughout the 18^th century, and when the topiary as an art form was revived in the 19^th century, more sculptural forms appeared.

Espalier

Espalier is a horticultural technique of pruning and grafting used together to train trees to create two-dimensional forms with the branches.  This technique was originally developed during the Middle Ages as a way to grow fruit trees within castle walls, without taking up space needed for other activities, and to add decoration to the walls.

Because these trees absorb as much sunlight as untrained trees, espaliers are ideal where there are issues of limited space.  Espaliers are able to grow well in cooler climates which would otherwise prevent the same species from growing successfully in a non-espaliered form.  Olives, figs, apples, and pears take particularly well to an espaliered form.  There are many different traditional shapes for an espalier, such as horizontal, palmettes (also called fans), cordons, and Belgian fences, among others.

Here are some sketches of traditional espalier patterns (images borrowed from www.southernaccents.com):

Horizontal Cordon

Fan

Triple-U

Belgian Fence

Candelabra

Pleaching

Pleaching is the art of training trees into a raised hedge, often in a two-dimensional, flat plane representation.  This technique involves the weaving together of branches, in which the branches are wounded and bound together at the site of the join.

Eventually, the trees will grow together through inosculation, a naturally occurring phenomenon similar to grafting.  From the late medieval times through the early 18^th century, pleached allées of trees were very popular in European gardens.  Trees with smooth bark, such as linden or sycamore trees were most commonly chosen for pleaching.

Grafting

Grafting is a horticultural technique of asexual propagation, in which the tissues of one plant are fused with those of another plant.  The technique dates back 4,000 years to ancient China and Mesopotamia.  Grafting is used on all different types of plants, with a variety of intentions – repair of damaged plants, hybridization, perpetuating clones, and optimizing pollination and cross-pollination, among others.  There are many different approaches to grafting a plant, such as inlay grafting, budding, and stub grafting.

Axel Erlandson was an American farmer, who utilized the technique of grafting to shape trees.  He opened his Tree Circus in California in the spring of1947.  Here are some of his creations:

Using Tree Shaping Techniques to Grow a Building

Ferdinand Ludwig, Oliver Storz, and Hannes Schwertfeger  – three young German architects at the University of Stuttgart’s Institute of Basics in Modern Architectural Design – have been experimenting with the concept of growing a building from willow trees, a process they call “building botany.”  They have experimented with building smaller structures built from trees, and they have investigated the elasticity of these trees and how well they grow around steel pipe.

The architects start by building a conventional support structure out of steel, resembling a scaffold.  Young willow trees, which are thin and are still flexible at a year old, are woven throughout the scaffolding.  The minimum height for these trees at the beginning of the project is ten meters, or thirty-three feet.  The trees are bent into the desired shape around the steel structure and are fastened into place.  As the trees grow and become stronger, they will assume the load-bearing function of the scaffolding, and the steel frame members will be removed, upon inspection by a structural engineer.  They expect the desired strength to be achieved over a few years’ time.

Because the growth of the trees is restricted, the roots of the willow trees grow sideways into containers of soil.  As the willows mature to a certain point, their roots are cut off, which will encourage the trees to grow into a single organism.

The structure of this living organism presents a different set of challenges.  Metal fasteners used to secure the trees to the steel frame can obstruct the flow of sap.  If this obstruction were allowed to persist, the trees would be strangled.  Ludwig, Storz, and Schwertfeger have devised a system of “sap bypasses” of branches, in order to keep the botanical structure alive.  They also must prune and otherwise maintain the structure in order to keep it from growing into unruly shrubbery.

The end goal of this endeavor is that when the willow trees achieve their full strength, the structure will be able to support an eight-meter, or twenty-six-foot, tall tower in South Germany.  Once the living organism is able to assume the load-bearing function of the tower, floors and roofs may be added.