Taxonomy: How to Describe a Plant 101

[Tum-thalas]

Are you ever asked to help identify a plant and the only information you are given is that it is ‘leafy’? Responding with something like “yes, they tend to be” is not really a solution to the problem. Not to be mean to those who do describe plants in such a manner but there are some words and terms that make it easier for others to figure things out. And it will then be far easier for us to tell you what your beloved mystery plant is.

Taxonomy is the practice and science of classification. Of all sorts of things, living or not. This is a fancy way of saying that things are put into groups and the group is given a name. Plants normally go like this (and I hope you remember it from science class):
Kingdom, Phylum/Division, Class, Order, Family, Genus, Species. Sometimes plants can go past the species level and be described as cultivars as well.

For example: the Peace Lily
Kingdom: Plantae (plants)
Division: Magnoliophyta
Class: Lilopsida
Order: Alismatales
Family: Aracaeae
Genus: Spathiphyllum
Species: Spathiphyllum montanum

Notice that the species name has two parts, the first of which is the genus.

Alright, enough of that babble. Here’s the gist: the leaf of a plant is not always round. Or oval. But what other shapes are there?

Sometimes the edges of leaves aren’t smooth. But what other kinds of edges are there?

Aren’t you glad that we have posted a bunch of helpful illustrations that may help you determine what the real shape of your leaf is? Or the strange name that the leaf margin(edge) is really called?

So here they are! And don’t stress out. We don’t expect you to remember them all by heart. We just hope you will use them if ever you need to describe some mystery plant.

Contents:
.Introduction.
.Structures.
.Roots.
.Leaf Shape and Venation.
.Leaf Margins and Attachment.
.Inflorescence.
.That's NOT a Plant!.

 

[Tum-thalas]

Know your root types? Here's a refresher.

Contents:
.Introduction.
.Structures.
.Roots.
.Leaf Shape and Venation.
.Leaf Margins and Attachment.
.Inflorescence.
.That's NOT a Plant!.

 

[Tum-thalas]

These illustrations show the typical way veins are arranged in leaves.


Both the tips and the bottoms of leaves have separate terms that are different from the overall shape name. Its important not to get too bogged down with the names. We don't expect you to memorize them, we certainly don't. Just take a look at the pictures and a mystery leaf. Which comes the closest?


These next illustrations have terms used for the entire shape of the leaf. Which comes the closest to yours?

Contents:
.Introduction.
.Structures.
.Roots.
.Leaf Shape and Venation.
.Leaf Margins and Attachment.
.Inflorescence.
.That's NOT a Plant!.

 

[Tum-thalas]

The types of edges(margins)of leaves tend to be a bit challenging. But we aren't looking for you to be perfectly correct as much as we are trying to get an idea of what it looks like. Just pick the closest.





Morphology is the appearance of an organism (shape, structure, pattern, color). These drawings show how a leaf can be arranged on a branch. When a leaf is attached to a branch by itself it is called a 'simple' leaf. But not all plants are like that. The stem of the leaf (called a 'petiole') is what is important to check. Is there only one leaflet or are there several leaflets attached to the same petiole before it attaches to the branch? A classic example of a pinnately compound leaf is the locust tree. Look closely.



Got that figured out? Yes but how does the leaf attach to the branch? Is one leaf straight across from another? Some plants don't have stems and the leaf seems to pop right out of the ground. These have basal attachment. Ferns are normally this way.


Some leaves don't have a petiole. They do that just to make things more difficult for you, ya know. Here's a few illustrations to help figure the whole 'petiole or not' issues you may be having in your life.

Contents:
.Introduction.
.Structures.
.Roots.
.Leaf Shape and Venation.
.Leaf Margins and Attachment.
.Inflorescence.
.That's NOT a Plant!.

 

[Tum-thalas]

"An inflorescence is: pretty. Yes, that is the technical term." -Flux_IX
It the way flowers are arranged on a plant. Even if it is just a single flower it is still called an inflorescence. They all look alike don't they? Yes, but they aren't. Here's a hint: branching.



A classic umbel is Queen Anne's Lace. A classic spadix is the flower of the peace lily or the Peperomia. Maple trees have the dangling catkin inflorescence. Is this helping?

Contents:
.Introduction.
.Structures.
.Roots.
.Leaf Shape and Venation.
.Leaf Margins and Attachment.
.Inflorescence.
.That's NOT a Plant!.