Simple leaf: a leaf that is not divided into smaller leaflet units.
Compound leaf: a leaf composed of two or more distinct blades, or leaflets.
Leaflets: a subunit of a compound leaf.
Not every tree has distinct bark like the shagbark hickory. When we’re identifying plants, one of the most useful things to do is look at the leaves, which are often very unique.
Plants with broad leafy foliage can have leaves that are either simple or compound. Simple leaves are all in one piece, like leaves from a red oak or elm tree.
Compound leaves may appear to be many leaves, but actually, this entire structure is one leaf composed of smaller pieces called “leaflets”. The leaflets are connected to form one whole compound leaf, which attaches to the branch the same way a simple leaf does. Like leaves from the staghorn sumac and the shagbark hickory.
There are some benefits to having compound leaves over simple leaves. Leaflets allow a compound leaf to absorb sunlight over a larger surface area and photosynthesize more efficiently. They also help prevent damage from the weather.
Like the sail of a ship, the wide surface area of a leaf might catch wind more easily, and rip the leaf or pull it away from the tree. But the segmented surface of a compound leaf allows for a more expanded surface area without sacrificing wind resistance, as wind can easily pass through the space between leaflets.
The segmented surface also limits a compound leaf’s number of pores, decreasing the amount of water lost through evaporation.
Checking out the trees above you, or picking up a leaf off the ground, can you identify any compound or simple leaves?