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Using Plant Identification Keys

Several of my plant guidebooks include plant keys. The directions for using plant identification keys are simple.

How to Use a Key

Each numbered entry has two choices. You pick the one that describes your plant. It directs you to the next numbered choice. One choice at a time you progress through the key until you arrive at a name for your plant.

I had my students devise keys in my classes. Each group was given a set of cards with imaginary creatures on them. They made up a series of choices and passed it to another group who was to use this key to identify the creatures.

It sounds so simple. Why is it so difficult?

using plant identification keys to confirm this is a black walnut bud
I thought getting a bud from a tree I knew would help me learn about the winter plant key. This is from a black walnut and has a very distinctive look. One part of the key asked me to split the twig lengthwise to see the pith. This is the soft center of a twig. In the case of the black walnut, the pith has a line of chambers. Other twigs have a solid pith. In cross section the pith can be round or have shapes. The practice did help a little.

Do you speak botanese?

The trick to using plant identification keys is understanding what the choices are. This understanding depends on knowing what the terms mean.

I have a new guidebook: “A Key to Missouri Trees in Winter” that uses terminal buds. I’ve looked at small plants for years, ignoring the trees. They are far over my head and I don’t climb trees.

That must change if I want to complete the Dent County Flora. This winter I am trying to identify some of the many trees growing around the place.

This book uses terms like opposite and alternate which I know. I think I know lenticels. Then there are leaf scars, pith, rounded or pointed and bud scales.

The terms aren’t too hard. It’s identifying them on the buds.

oak buds
Oak trees don’t drop their leaves so I could look at the dried leaves on this tree and see the silvery bark in long strips. The leaves put this tree in the white oak group. There are several species in the group. The winter key was the place to try. Except I ended up at Carolina Buckthorn, not oaks. I backtracked from oak and might know where I made a mistake, not that I won’t make the same mistake in the future. On the oak key, the bud keyed out to white oak. I’m waiting for spring leaves to confirm this.

How am I doing?

So far the oak bud – I know it’s an oak – keyed out to Carolina Buckthorn. The black walnut bud did key out correctly. I cheated on the Osage Orange and Sassafras.

Simple as they are, using plant identification keys is not simple. There are several more trees I do know like redbud and dogwood I can practice on.

Then again, spring isn’t that far away. Leaves will appear.

cover for "Exploring the Ozark Hills" by Karen GoatKeeper
Many of the nature essays in this book are about plants found in the Ozarks.

By Karen GoatKeeper

Karen GoatKeeper loves to write. Her books include picture books, novels and nonfiction for science activity books and nature books. A recent inclusion are science teaching units.
The coming year has goals for two new novels, a picture book and some books of personal essays. This is ambitious and ignores time constraints.
She lives in the Missouri Ozarks with her small herd of Nubian dairy goats. The Ozarks provides the inspiration and setting for most of her books.