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Tree Shapes: Pyramids, Lollipops and Vasesby Contributor January 25, 2016
Different tree species have different characteristic features. The leaves of a maple tree (Acer spp.), for example, differ from those of a sycamores (Platanus spp.); just as the bark of pine trees (Pinus spp.) differs from that of redwoods (Sequoia sempervirens). Myriad other examples exist, such as the manner in which the roots typically form, and the type of fruit and flowers produced by the species. Property owners often consider these criteria when selecting trees for their yard. For example, some place a premium on beautiful flowers, while others prefer a tree that does not create a lot of litter. However, all too often, property owners neglect to consider an important characteristic feature of trees -- the shape of the crown. Most botanists and tree professionals recognize seven basic tree shapes, but there is variation -- some authorities recognize more or less than eight. None is intrinsically better than the others are; personally, I tend to like round or oval trees, but perhaps you prefer trees that grow in a columnar shape. Different strokes for different folks, and all that.
Round tree crowns are rather common, and look exactly like you would expect them to. Examples of trees that produce a round crown include white oaks (Quercus alba), European lindens (Tilia europaea) and paperbark maples (Acer griseum).
Admittedly, the difference between a tree with a round crown and one with an oval crown can be subtle, but at the extreme ends of the spectrum, the differences are obvious. Oval-crowned trees include downy serviceberries(Amelanchier arborea), sugar maples (Acer saccharum) and frontier elms (Ulmus ‘Frontier’).
Trees that produce tall, narrow crowns are said to have a columnar growth habit. Such trees are helpful for making hedges and privacy screens. Trees that typically produce columnar crowns include Lombardy poplars (Populus niger‘Italica’), red cedars (Juniperus virginianus) and emerald arborvitaes (Thuja occidentalis ‘Emerald’).
Some trees tend to form broad crowns that expand horizontally; botanists describe their growth habit as “spreading???. Examples of spreading trees include live oaks (Quercus virginiana) and London plane trees (Platanus x acerifolia).
The vertical branches of some trees tend to fall outward, giving the crown a vase-like. Vase-shaped trees offer a few unique benefits over some other tree shapes, as they provide a good deal of shade, yet they do not often block sidewalks and sight lines at ground level. American elms (Ulmus americana), Green Vase zelkovas (Zelkova serrata ‘Green Vase’) and crepe myrtles (Lagerstroemia spp.) all exhibit vase-like growth habits.
Pyramidal trees produce crowns that are widest at the bottom and come to a fine point at the top. Examples of trees that exhibit pyramidal growth tendencies include blue spruces (Picea pungens), Deodar cedars (Cedrus deodara) and Leyland cypresses (Cupressus x leylandii).
The branches of some trees tend to droop toward the ground. This produces a characteristic “weeping??? crown shape that is characteristic of weeping willows (Salix babylonica), weeping figs (Ficus benjamina) and numerous cultivars.
*** Next time you are planning to install trees on your property, be sure to consider the shape of the tree before making your selection. If you want to place a privacy screen in the relatively small gap between your house and your neighbor’s, do not select a bunch of vase-shaped trees, which will likely grow too close to the top of your home. Instead, select a species with a columnar growth habit. While it is true that you can often prune a tree into the shape you would like, this is not the wisest course of action. Such an approach is labor- and cost-intensive, and forces the tree to adapt to stressful circumstances. Instead, simply start with a tree that naturally grows into the shape you like best.
We know some great people for San Francisco tree pruning who can help you determine which trees will work best for your property, so give us a call and let us help!