Tree Architecture

Architecture is a term usually applied to our built environment, but it also can apply to natural systems - to trees, for example. Trees are naturally programmed to grow in predictable patterns that are unique to each species.

Buildings are constructed in Greek Revival or Postmodern styles, but nature constructs trees in coffeetree or river birch styles. Many people think of trees in terms of their flower color, foliage and attractiveness, but their most significant characteristic is their natural style or architecture.

Perhaps the most obvious architectural feature of trees is their size. The range of variability is tremendous. In Missouri, tulip poplar in the Bootheel region can reach over 150 feet, while the shrublike wild plum tops out at around 12 feet in a north-central fencerow. In the forest, oaks, hickories, ashes, maples and lindens form a lofty branch canopy over the subservient ironwood, redbud and serviceberry, which compete for limited sunlight in the understory.

Another important aspect of tree architecture is branching habit, or the natural arrangement of trunk, limbs, branches or twigs. Some trees develop a pronounced central stem extending to the top, resulting in an overall conical or pyramid tree shape. This is called "excurrent branching" by botanists.

Species that conform to this branching habit are the familiar needled evergreen pines, spruces, junipers and the deciduous baldcypress. Some trees have strong excurrent branching in their youth, but gradually give way to a more spreading shape in old age. Examples include pin oak, sweetgum, blackgum, lindens, sycamore and tulip poplar.

Trees that grow by dividing their main stems into multiple, equal-sized branches, as opposed to one main stem, are botanically known as "deliquescent." Trees with this growth habit tend to develop a fan or V shaped outline. Examples of this type are the once familiar American elm, hackberry, honeylocust, yellowwood and redbud.

Knowing a tree's growth habit, together with landscape position, can be used for identification. The coarse, light-colored branches of sycamore make it stand out from other trees, especially in winter. The conical shape and stiffly arranged horizontal side branches of pin oak make it easy to spot.

Dense, reddish-twigged trees in low areas are likely willows. Pole straight evergreens with sparse bottom branches on Ozark hilltops are shortleaf pine. Many other trees have signature characteristics which are actually more distinct when viewed from a distance.

A practical application of tree architecture is planning for tree planting and care. Need new street or shade trees?