Witness Tree Quest

INSTRUCTIONS FOR RECORDING A WITNESS TREE

Although much of our North Shore area was heavily logged in the 1800s, Lake Bluff was not.  We may have trees that predate the first settlers’ arrival in Lake Bluff in 1836.  Oaks can live for several hundred years, so we may even have trees that were here when our country was founded in 1776.

Let’s see if we can find our oldest trees and appreciate the history they have witnessed.  Here is how to record a notable older tree:

1.  Find a tree with a wide trunk.

Age is indicated by the width of the tree trunk, and native trees will be our oldest trees.  Look for trees within the limits of School District 65 on both private and public property.  

Because different species grow at different rates, slower-growing hickory or walnut trees will have a smaller trunk than an oak of the same age.  Likewise, a fast-growing cottonwood or silver maple will be younger than an oak with the same-size trunk.

2.  Identify the species.

The easiest way to do this is by uploading a photo to the PictureThis website on its Identify Plants tab.

There are also a number of smartphone apps that will identify the species of a tree.  PictureThis is the most accurate, but there are a number of others available, such as Seek and PlantNet.  All are either free or have a limited free version.  Photos taken with an iPhone will provide an ID if you press on the letter “i”.

If you love botany, there is a tree identification aid on the Morton Arboretum website.  You can also request help from the Witness Tree team if you are not sure of the species.

3.  Measure the trunk diameter.

At a height of 4.5 feet above the ground, measure the circumference of the trunk, in inches.  Divide the circumference by 3.1416 to determine the diameter, often called its DBH.  If the tree has more than one trunk, measure only the largest trunk.  Don’t measure around multiple trunks.

4.  Estimate its age.

Multiply the diameter by the species growth factor from the table below, and you will have an age estimate in years.  This gives only an approximate age of the tree because tree growth is affected by many factors, such as drought and the amount of sunshine that reaches the tree.  

5.  Geolocate the tree.

Using a mapping program on a smartphone, drop a pin at the tree location and record the coordinates given.

6.  Submit an entry form.

Obtain a form at the Village Hall, the Lake Bluff Library, the Park District Office, the History Museum, the little free library in Artesian Park, at the Farmer’s Market, or download the form below.  

Fill out the form and drop it off at the Village Hall, Park District, the Library, the History Museum or email it to:  growingnativegardenslb@gmail.com.  You may also email questions to that address.

The Quest will begin on May 1 and conclude on September 30, 2026.

About our growth factors.

The growth factors provided below are based on research done by the Morton Arboretum as quoted by Friends of the Wildflower Garden, Inc., Minneapolis, MN.