What are the types of leaves? Classifying leaves is often an exhaustive pursuit because there are so many factors involved in the process of determining into what category a leaf should be placed. The criteria for classification include traits such as leaf shape, complexity, stem or lack of stem, and the edge of the leaf itself. These traits break down into further categories and so on, which is why entire fields of study and publications are devoted to understanding what appears on the surface to be quite simple, but what is scientifically very complex. Let’s approach the many types of leaves from a beginner’s standpoint and take it from there.
Leaves fall into one of two categories: simple or compound. Whether a leaf is simple or compound relies entirely on where the bud is located. At this point, a basic understanding of leaf structure and terminology is necessary. To simplify things, let’s take it step by step. First, we have the axil of the leaf, which is a scientific term used to refer to the angle between the stem and a leaf.
Next we have the petiole, which is simply a term for the leaf stalk itself (in other words, the narrow potion of the leaf attaching it to an object, such as a tree branch. The bud, in botanical terms, is a growth found at either the end of the stem or possibly near the axil. Finally, as far as terms go for the soft parts of the leaf, we typically know some, if not most. There is the leaf’s vein, through which water is transported, the tip (or shaped end) of a leaf, and the blade, which is sometimes referred to in the scientific community as the lamina. As mentioned, categorizing types of leaves can be a very complex pursuit.
Still paying attention? Fantastic. Let’s get back to simple and compound types of leaves. If you happen to be strolling along one day and pick up a leaf, you might notice that it has a bud growing from the axil. In this case, it is a simple leaf. If, on the other hand, the leaf is clustered into many smaller leaves, it is a compound leaf. It’s easy to visualize a simple leaf as, for example, a single walnut leaf. A compound leaf might look a bit like something fallen from an ash tree.
Within the compound leaf category, we have leaves known as palmate leaves. These types of leaves resemble their name (palm) and have leaves branching outward. The largest is in the middle, flanked by smaller, and then so on. Another compound leaf is the pinnate, which looks rather like a plant itself. Imagine a thin stem with multiple small leaves branching out on each side almost symmetrically and you have, in your mind, a close idea of what a pinnate leaf looks like. If you’re curious, bipinnate leaves are types of leaves which are simply divided twice more (hence the prefix bi-) with stems branching out on both sides and symmetrical leaves flanking each stem.