What’s Growing in Your Garden? A Guide to Plant Identification

by on November 15, 2012Wilma Stordahl

Some plants are so common everybody knows them. A rose, for example, would be hard to confuse with any other flower. But what if there are no flowers present? Most plants only flower for a fleeting two to three weeks a year. Would you know a rose bush if it did not have any flowers on it?

Ok. That was an easy one. What about Hydrangea macrophylla? Would you be able to identify a hydrangea if it had no flowers? Some of you can. Others are asking, “a hydra what?”

Identifying Plants: Why is it Important?

plant identification guidesIdentifying plants seems easy if you’ve been doing it for years, but most people can’t tell the difference between a boxwood hedge and a holly hedge, a Douglas fir and a Western red cedar, or a salmonberry and a raspberry.

Learning to identify the plants in your garden is a skill that will help you avoid mistakes in how you maintain your landscape and what you buy at the nursery. Some plants need a lot of water. Some don’t need much at all. That tree might look cute in its gallon pot at the nursery, but did you know that in 10 years it will be 30 feet tall and 10 feet wide?

Identifying plants in your garden can also help you to identify those that may be poisonous and toxic to pets and children. For example, that shrub in your garden may look lovely, but you might decide to move it to an area that is inaccessible to your dog once you discover that every piece of it is poisonous.

At a minimum, set out to make a list of the garden plants that currently exist in your garden. If you don’t have a clue where to begin, it can be well worth it to hire a landscape designer or ask a neighbor with a green thumb to help you create an inventory identifying the plants in your garden.

How are Plants Identified?

Every organism on earth that has been found, named, and classified can be identified using identification keys.

A super serious gardener or botanist may use a botanical identification key when identifying plants. Plant identification keys ask about leaf shape, leaf disposition, flower color, number and arrangement of stamen, and so on until the plant’s identification can be made. Each plant family has certain characteristics, and by using a plant identification key, a botanist can narrow down her choices until the plant’s family is determined. From there, the genus is decided, and, finally, an identification of the species is made.

Obviously, identification keying is for serious plant geeks, and typically the best resource for this level of information is the botany department of a local university. Both the University of Ohio and Colorado State have virtual plant science libraries. Neither website is very pretty, but they are well-linked.

Identifying plants can be tricky, but the macro characteristics to look for are overall plant shape; leaf arrangement, shape, color and size; bark patterns, thickness, and markings; and flower color, petal arrangement and number.

I know. Some of you are thinking, “I thought leaves were green,” but the difference between dark green, light green, blue-green, shiny green, and chartreuse can distinguish one plant from another.

A Guide to Plant Identification Guides

Any gardener, hiker, or woodland forager should own at least one good plant identification guide. In my own home I have fourteen different reference books on plant identification. They range from the slim yet informative “Wetland Plants of Oregon and Washington” to the three-inch thick “A-Z Encyclopedia of Garden Plants” published by the American Horticultural Society.

Now, the average gardener doesn’t need a whole shelf of plant identification guides, but the point in telling you about my personal collection of reference books is to illustrate that it is difficult, if not impossible, for one book to cover all of the plants of the world, or even one region.

The important thing is to find a plant identification guide that suits your experience level and purpose. If you are a hiker who likes to nibble things along the trail, get yourself a good trail guide with pictures and good descriptions. One of my favorite plant identification guides for this purpose is “Plants of the Pacific Northwest Coast” by Pojar and MacKinnon. When I was taking forestry classes at the University of Washington, we simply referred to this book as “Pojar.” You had to have Pojar in your backpack on hikes. I still do.

For the average gardener, The American Horticultural Society publishes garden books for every major region of the country. These have a lot of pictures and list the garden plants most popular and easy to grow in each region. If I were a novice gardener, I would use one of these books in conjunction with some Internet research to identify plants in my garden.

Another very popular garden book for gardeners in the western United States is the “Sunset Western Garden Book.” It does not contain as many pictures as the American Horticultural Society’s garden books, but the plant descriptions are much more comprehensive. For the average gardener, this is, hands down, one of the best garden plant identification guides around.

As you can see, identifying plants can be difficult and overwhelming for new gardeners. Start by figuring out what you have, and learn as you go, identifying one plant at a time. Pretty soon, you’ll be amazed at how much garden knowledge you have accumulated.

What specific questions do you have about identifying plants? What are your favorite plant identification guides? Please comment and let us know.

{ 2 comments… read them below or add one }

Wilma March 19, 2013 at 6:24 pm

Hi Wendy,

It’s difficult to know without a picture, but it sounds like the plant you described could possible be your oregano. Basil and dill only grow for one season, unless you’re lucky enough to have them come back from seed. Dill, of course, has very wispy leaves, and basil has leaves that get to be about 2 1/2″-3″ long. Thyme has small oval leave, about a 1/4″ long.

The leaves of oregano are about 1/2″ – 3/4″ long and about a 1/2″ wide. The leaves of oregano are also slightly fuzzy and light green. However, the purple veins are throwing me off. While the stems can look a little purple, the venation on the leaves is usually not purple. Make sure you make a positive identification before you use this plant in any food. Some weeds can be poisonous or cause hallucinations. Here are some good pictures of oregano, http://www.bing.com/images/search?q=oregano&FORM=HDRSC2,

If you’re still unsure, take a leaf with you to the grocery store. Find fresh oregano in the produce section and compare the leaves.


Wendy March 19, 2013 at 10:50 am

I planted a herb and then threw away the packet. I don’t know what it is. My herbs I planted are: dill, basil, oregano, and thyme. My guess is that it’s oregano; however, I can’t seem to find a picture of it on the internet that does it justice. It has small almond leaves that are light green with purple veins running through it. It has a real pungent odor. Any ideas?


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