Pyrus calleryana ‘Jaczam’
This tree profile is shared for educational purposes. Urban Forest Nursery does not currently grow this variety, but it remains part of ongoing discussions around urban tree selection.
UPDATE 2026: All flowering pears have fallen out of favor in many locations in recent years because of disease and insect susceptibility, and poor structure. We also observed that as the ‘Jack Pear’ aged, the somewhat tight structure in youth gradually was lost with lateral limbs splaying out more than desirable. We no longer grow this cultivar but have heard that some pears do perform better in dryer climates. Check your area for specific tree performance. How often are you asked, “I need a small tree, one that stays small”? Choices are limited because even most “small trees” will reach 30 ft. or more. The “Jack” Pear is one of the exceptions. Literature says it may get to 20′ tall and 10′ wide in 30 years. Our specimen planted 10 years ago measures about 13′ tall by 7′ wide under excellent growing conditions.
The crown is dense, with closely spaced branches, and growth is even, very upright, and much denser than other calleryanas. The spring flower set is spectacular, with white flowers covering the tree completely, creating a pure white globe. As flowers fall, small dark green roundish leaves form an even denser canopy. The form and appearance nearly remind me of a hot air balloon with the lower limbs reaching straight out to hold the canopy in place. Our fall color has been yellow to bright red depending on the season, but it apparently does color up regularly in colder climates.
This pear tree appears to transplant easily, like all flowering pears. We have observed small fruit, also dependent on the season and if planted near other pears.
By the way, there is a “Jill” Pear, Pyrus calleryana ‘Jilzam’, also. The form on the “Jill” is about the same height, but a little broader with age. The branching habit is more scattered and less uniform. And no, I am not joking.
Let me know if you have any experience with these or other trees that you would like to pass on.
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Jim Barborinas
Owner of Urban Forest Nursery, Inc.
ISA Certified Arborist #0135
ASCA Registered Consulting Arborist #356
15119 McLean Rd.
Mount Vernon, WA 98273
jim@urbanforestnursery.com
What should I know about Jack Callery Pear (Pyrus calleryana ‘Jaczam’)?
Here are some common questions we hear from people considering this tree:
We no longer grow this cultivar due to a combination of concerns that developed over time, including susceptibility to disease and insect issues as well as structural weaknesses as the tree matures. Its form also tends to become less consistent with age, which reduces its long-term reliability.
In its early years, this tree is known for its dense, upright growth habit and strong central form. It produces a heavy display of white spring flowers that can create a striking visual effect, followed by small green leaves that create a very full canopy. Fall color can range from yellow to red depending on conditions.
It establishes easily and grows into a compact, relatively small tree compared to many other landscape options. However, as it matures, the branching can become more open and less structured than expected, which can affect its long-term appearance in formal settings.
While it stays relatively small for a tree in this group, its canopy can shift from a tight, uniform shape in youth to a broader and less predictable form as it ages. This change in structure is one of the main reasons it has fallen out of favor for consistent landscape use.