PSC 2620: Woody Trees and ShrubCourse HomeWeek 11

Acer negundo - Boxelder

Plant Viewer
During the spring the tree has plentiful blooms that form at the terminal bud of the branches. The flowers are arranged in 5-12 inch long panicles. The actual species has white blossoms.
The large leaf is palmately compound. It has 7 obovate leaflets with serrated margins. The tree is a favorite feeding spot for Boxelder Bugs and attract them in droves during the summer. Image: Bruce Marlin

Plant Description

Acer negundo, or Boxelder or Ash-leaved Maple, is a large and hardy shade tree that many consider a trash tree because of its insect problems and weak wood. It grows 30-50 feet high with a slightly wider spread. It has a broadly rounded form, usually with a great deal of irregularly in the crown. It grows natively in moist conditions, but is highly adaptable to nearly any soil or moisture condition.

The bark is gray with tightly spaced deep ridges and furrows. New growth has a reddish overcast to it. Yellow-green flowers appear in the spring. Male flowers are in small clusters and female flowers are in hanging racemes. Neither could be considered ornamental. The samaras are held in paris at a steep angle. They form profusely in long chains and drop from the tree in October. New seedlings emerge in copious amounts.

The bright green leaf is opposite pinnately compound and 5-8 inches long. It has 3-5 leaflets, each leaflet being ovate in shape and roughly serrated. The leaf is similar in appearance to that of Fraxinus pennsylvanica. The leaves turn an unimpressive dull yellow or brown color in the fall.

Landscape Use

I recommend not using Boxelder except in particularly difficult locations, where the tree is well-suited. It is a maintenance liability and not particularly an attractive tree. Locations with poor soils, and extremes of either drought or damp are ideal locations. Use it as a last resort.

Points of Interest

Boxelder is famous for being attractive to Boxelder bugs, which feed on the tree, and anywhere the tree is planted is sure to see a herd of the insects. It also regularly develops large burls on the trunk that give it an unsightly appearance. Acer negundo has brittle wood that often breaks in wind or under the weight of snow.


Notable Cultivars

Flamingo
One of the few cultivars worth considering for use as a shade tree or lawn tree. The leaf is variegated with green and cream, with the new leaves and shoots being tinged a pure pink. It grows 25-30 feet high and wide. Branches that have reverted to regular green leaves emerge regularly and should be pruned out immediately.