Introduction to the Boxelder Tree
Boxelder, also known as ash-leaved maple is one of the most common and adaptable urban trees in North America - it also may be the trashiest. I include this tree in my 10 worst trees to plant in your yard and planting it next to the house is probably not a good idea.
The best thing about the tree is that it is comfortable on poor sites sites where more desirable trees cannot maintain adequate health for long life. It is very commonly seen in the treeless plains and western United States as a street tree. You can use the tree for quick growth but plan to interplant with more desirable trees to provide for a lasting tree canopy. Boxelder can be a treasure on adverse tree sites.
The scientific name of boxelder is Acer negundo and is pronounced AY-ser nuh-GUHN-doe. Common names include ashleaf maple, Manitoba maple and poison ivy tree and the tree is a member of the plant family Aceraceae. Although considered by many a "maple outcast", it is indeed in the maple family and the only native maple with more than one single blade or leaflet on a single leaf stalk.
Boxelder grows in USDA hardiness zones 3 through 8 and is native to North America. The tree is sometimes crafted into a bonsai specimen but often used as a screen/wind break and for land reclamation. It grows rapidly, can become very large and needs a lot of space. Boxelder is still a very common tree to see in a yard or park west of the Mississippi river.
There are several attractive cultivars of boxelder including ‘Aureo-variegatum’, ‘Flamingo’ and ‘Auratum’. The cultivar Acer negundo ‘Aureo-variegatum' is noted for its leaves bordered in gold. Acer negundo ‘Flamingo’ has variegated leaves with pink margins and is somewhat available at local nurseries. Acer negundo ‘Auratum’ has abundant gold leaves but is a little harder to find. You must remember that even though these cultivars are ornamental, they still share the original boxelder tree’s undesirable characteristics that include unattractive female fruit and breakage that increase the chances of the tree's early removal due to quick growth.
Problems With Boxelder
Boxelder is a rather nasty tree where limbs break with a vengeance - a landscape maintenance night mare. The fruit droops in clusters which some describe as looking like "dirty brown socks" which adds to the overall trashy look of the tree. The boxelder bug makes things even worse.
Boxelder bug or Leptocoris trivittatus loves the boxelder tree. This half inch red-striped insect is a true pest during winter where the adult multiplies and invades homes near where boxelder trees grow. It is one of the most common household pests in the United States. The bug emits a foul odor, stains fabric and can cause asthmatic reactions. It does no harm to the tree.
Boxelder in the landscape grows to a height of 25 to 50 feet, depending on tree variety and site conditions. One of the tallest ever measured had a recorded height of 110 feet. The tree's crown spread is 25 to 45 feet and the crown is typically broad and ragged or disheveled. The tree often has multiple furrowed trunks or very squat single trunks.
Flowers are without petals, dioecious and yellowish green and the female tassels are very conspicuous. The very maple-looking seeds, called samaras hang in long, profuse clusters and stay on the tree throughout winter. Nearly every seed is viable and will cover up a disturbed area with seedlings - a very prolific seeder is boxelder.
Boxelder Leaf Botanics
Leaf arrangement: opposite/subopposite
Leaf type: odd pinnately compound
Leaflet margin: lobed; serrate
Leaflet shape: lanceolate; ovate
Leaflet venation: pinnate; reticulate
Leaf type and persistence: deciduous
Leaflet blade length: 2 to 4 inches
Leaf color: green
Fall color: orange; yellow
Fall characteristic: showy
I explain some of these terms in my Botanical Glossary...
You will have to prune this tree! Boxelder branches droop as the tree grows and will require pruning if you have regular walking and vehicular traffic under the canopy. The tree form is not particularly showy and as I have mentioned should be grown with one single trunk to maturity. The tree is susceptible to breakage and can occur either at the crotch due to poor collar formation, or where the wood itself is weak and tends to break.
Superior Western Boxelders
After trashing this "trash" tree I must mention the superior qualities of boxelders in the West. Seems that the tree takes on positive characteristics in the west that is not seen in trees in the eastern half of North America. California interior boxelders take on yellow and red colors in autumn that rivals eastern maples. Its drought tolerance makes the tree a welcome plant in that dry country landscape and very easy on limited water resources.