Tree Burls

Photographer: Dale L. Hugo
Summary Author: Dale L. Hugo

Within two blocks of my house in Arlington Heights, Illinois are two very different burls on two different species of trees. One is on a mature soft maple tree (Acer saccharinum). Notice the Boy Scout hatchet (circa 1956) next to the burl. For size comparison, the hatchet is exactly 13 in (33 cm) long. I have no plans to harvest the burl! The smaller burl grows on a Russian olive (Elaeagnus angustifolia, Russian silverberry, or oleaster). It’s exuded some very dark sap, a precursor to forming fossilized amber, and is sufficiently hard that the penny used for size comparison could not scratch it.

The sap seems to have exuded from the inside out. I wasn’t able to detect any insects in the amber, which was quite dark. The burl, basically a benign tumor, on the soft maple has grown very slowly over the years. I estimate that the age of the tree is roughly the age of the Hasbrook subdivision -- built in 1961-1962. The Russian olive is probably about 35 years old and was planted by a former owner. It's near the end of its lifespan and has recently lost some major limbs due to heavy snowfalls and ice storms. The burl on this tree seems to be growing very slowly over the site of a former injury, possibly due to loss of a limb approximately 20 years ago.

[12/18]