It's classified...

At the start of the school year I give lots of classroom presentations about trees.  The students learn about the jobs that different parts of the tree do and about the process of photosynthesis.  The favorite parts of the presentation for the students (and me) are the hands-on activities involving dendrochronology (the study of tree growth rings) and leaf classification.  I've written about both subjects multiple times - look here and here for dendrochronology posts; leaf classification posts can be found here and here.

Today I thought I would share a little bit more about leaf classification.  The following few images are basically the same as the introduction to leaf classification/identification that I give in class.  

With this information you should now be able to classify the leaves of Michigan trees as well as any third grader!

Here are the leaves of forty Michigan species.  Where do you think they fi tin the classification system?  Needle-leaf or broadleaf?  If its a broadleaf, is it simple or compound?

 

 

 

Northern White Cedar - An important winter food source for White-tailed Deer

On two recent occasions I have visited locations with Northern White Cedar (Thuja occidentalis) trees.  This tree is typical found in wet, mucky soils in swamps, floodplains, and along the edges of lakes. The picture above (and the following two pictures) show Northern White Cedars growing in the Chippewa River floodplain at the Chippewa Watershed Conservancy's Sylvan Solace Preserve.  The Cedars at Sylvan Solace are restricted to this narrow band of muck soil along the edge of the river.

The next two photographs were taken at Mission Creek Woodland Park in Mt. Pleasant.  Mission Creek Park is a mixture of upland and wetland habitats.  Along Mission Creek itself is a section of swamp filled with Norther White Cedars.  Because these trees grow in habitats with a high water table, they often have very shallow root systems and are prone to toppling over in high winds or even when snow or ice builds up in their branches.  On a walk through the park last week I noticed several trees that had recently fallen over.

Northern White Cedar is a preferred winter food source for White-tailed Deer.  Often deer will eat every needle from a tree that is within their reach to a height of 6-8 feet off the ground.  In areas with a large deer population, cedars can have a difficult time reaching adulthood, they are often consumed before they have the chance to grow out of the reach of deer. 

When a mature tree such as this one falls deer are quick to discover this easy source of food.  Many of the needles on this tree have already been stripped by hungry deer.  I expect that before winter is over, the deer will eat every needle that they can physically reach.

Tree ID

One of the first lessons that I teach third grade students is how to classify leaves.  They learn to differentiate between needle-leaf and broadleaf species; then they learn how to tell the difference between simple leaves and compound leaves.

If you are scratching your head right now.  It's easy.  A needle-leaf tree has leaves shaped like...wait for it... a needle!

In contrast, a broadleaf tree is any tree that is not a needle-leaf.  Instead a broadleaf tree has broad (or wide) leaves.

Broadleaf trees can be further divided into simple leaves and compound leaves.   

Simple leaves are those that have one leaf on one stem.  The shape and size of the leaf do not matter; if the leaf has only one part it is a simple leaf.  That leaf can have smooth edges, serrated (toothed) edges, or edges that are divided into lobes.  See, it's simple!

In contrast, compound leaves are not simple.  Instead of having one leaf on one stem, compound leaves have one stem with multiple leaflets.  These small leaflets are each distinct from one another - meaning that they are not connected to each other, but only to the stem that they share.

To make this leaf classification activity more memorable for students, I have collected dozens of real leaves.  These leaves have been pressed, allowed to dry and them laminated on a sheet of 8.5" x 11" cardstock.  Unfortunately, due to class sizes, I often need as many as ten different sets of leaves for student groups to work with.  This means that sometimes I do not have enough real leaves to go around.  So to fill out my leaf sets, I pick one real leaf of each species and create a color scan. 

Here are my scans of the leaves of forty different species that can be found here in Mid-Michigan.  Please feel free to save and print these images as needed.