As information has become more widely available, homeowners and property managers have begun selecting better trees for the spaces they have available. Fewer people are planting giant eucalyptus species in tiny spaces, and several small species, including redbuds and Japanese maples, have become more popular.
However, height and spread are not the only characteristics of a tree that determine its suitability for a given space. You must also consider its water and lighting needs, soil preferences and the shape of its crown. Crown shape – our topic for today – is especially important, as it can help you predict how the tree’s canopy will fit into the space provided.
Common Tree Shapes
Different authorities categorize shapes in slightly different ways, and some impart more specificity in their categorizations than others. But these types of subtle distinctions are rarely important to homeowners and property managers. It is merely important to recognize the basic crown shapes available so that you can select a species that will likely thrive in the space available.
Some of the most commonly recognized tree shapes include:
Columnar trees have tall, narrow crowns. They are ideal for narrow planting spaces, and they can help accentuate vertical points of interest, such as structural columns or long windows. Some arborists and landscapers distinguish between columnar trees, which have 5:1 height-to-spread ratios, with fastigiate trees, which have ratios closer to 10:1. Other professionals use the two terms interchangeably.
Most columnar or fastigiate trees are cultivars, as this shape is not especially common in nature. There are a number of columnar conifers available, including Italian cypresses, arborvitaes and blue spruces. But there are also sweetgum, maple and oak cultivars that grow in columnar or fastigiate shapes.
Pyramidal trees (which are also called conical) have a very narrow crown at the apex, which gradually widens toward the ground. The classic image of a Christmas tree is a great example of the pyramidal crown shape, however, many trees grow in this characteristic shape, as it helps the leaves on lower branches avoid the shade cast by the higher branches.
A few great examples of pyramidal trees include American hollies, blue spruces, gingkoes and pin oaks. Additionally, several arborvitaes and juniper cultivars have been developed.
Round trees have a lollipop-like appearance. Some authorities distinguish round trees from those with oval-shaped crowns, but this distinction is rarely very important. Oval-shaped trees can provide privacy to second story windows, while not blocking walkways and doors near ground level.
Some of the most common trees with round canopies include camphor laurels, yellow bloodwoods and apple-box eucalyptuses. Several cultivars – including silver birches, a number of gum trees and several citruses – with round crowns are also available.
Irregular trees have, as their name implies, unstructured crowns, which are difficult to describe in simple terms. Because their crown shape is somewhat unpredictable, irregular trees should typically be planted in open sites, which do not impose many size constraints.
Some of the most notable trees with irregular crowns include plane trees, sycamores, hickories and smoketrees.
Weeping trees have long, pendulous branches, which spread widely from the central trunk as they grow. The ends of the branches droop down toward the ground and may even occasionally contact the earth in some cases. Weeping trees are usually planted as specimen trees, which serve as the focal point for gardens and properties.
The weeping willow is undoubtedly the most popular tree with a weeping growth habit, but a number of cherry, spruce, willow and cedars are available in weeping cultivars.
The branches of vase-shaped trees spread out, although not as much as those of weeping trees. Vase-shaped trees are often planted on both sides of roadways to create a tunnel-like effect. Smaller species can be used to create similar tunnels over walkways and sidewalks.
American elms have very distinct vase-shaped canopies, but Kousa dogwoods, redbuds and quaking aspens also exhibit vase-like canopies.
If you need help selecting a good tree shape for the space you have available, give your friends at Trav’s Tree Service a call. One of our skilled arborists will visit your property, analyze the growing conditions and space available and provide you with species recommendations. This will help ensure your new tree fills out the new space well, without growing too large or encroaching on your home or nearby power lines.