Description

• Ultimate height and width: Potential to grow over 30' but usually reach a height, and width, of 20 feet in urban environments.
• Foliage: Although not spectacular, the foliage will change from green to any number of colors from yellow to purple in the fall (depending upon the particular species)
• Trunk/branch/trunk characteristics: Thorns are located throughout the branches. Hawthorns are small, low branching trees, and if left unpruned (trained) the tree will produce a very congested branching pattern inside the tree's crown. 
• Flower/fruit: Flowers are usually white and the fruit resembles small crabapples. 

CPTED Properties:

• Access Control - Hedges define entries and exits, and can direct travel and movement, even reducing or eliminating access. It has been my experience that the best hedge to keep man or animal from crossing is a hawthorn hedge. Many hawthornes have a tendency when left unpruned (untrained) to produce several trunks and grow into a large shrub. This can be accelerated, and perfected, with pruning to promote a hedge like appearance with hawthorns planted in close proximity to one another. If the end product is to have the hawthorn serve as a small tree make sure a tree-form species is selected and the tree is pruned young to promote good structural form and shape.  
• Aids Natural Surveillance
• Territoriality - Hedges, when properly maintained, help establish territoriality by defining boundaries and providing multiple opportunities through the year for the property owner to prune. Tree may appear to be "messy" during years in which a large amount of fruit is produce and if the tree is susceptible to fireblight, rust, or other diseases.

Requirements

• Hardiness & Urban Toughness: USDA Zones 4 to 8. Once established, hawthorns are able to live a relatively long time in most urban environments. Many species/varieties are susceptible to fireblight (disease).
• Light
• Potential Urban Conflicts - Fruit may create a mess on paved surfaces. Low hanging branches could pose a serious threat to pedestrians (intended users). Utility friendly!

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Note: The fact that there are over 1,000 species of hawthorns in North America makes it difficult to even attempt to generalize characteristics that may be common to most hawthorns. This diversity springs from promiscuous nature of hawthorns which readily hybridize with one another.