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Plant Comparison and ID Guides

October 30th, 2019 by Alex Zorach

One of the biggest challenges with plants is accurately identifying them. Many people do not even have names for the majority of plants they see as they go through the day. Even among gardeners and others who work closely with plants, misidentifying plants is common.

Why is plant identification important?

Plant identification opens the door to learning about individual plants and enables us to make better choices involving plants. Knowing a plant's name enables you to research its range, native vs. introduced status, growing conditions, growth habit and characteristics, ecological relationships, uses, control methods, and more.

In many cases, ID characteristics and ecology go hand in hand. For instance, the smooth bark of the American beech (Fagus grandifolia) reflects its vulnerability to fire, whereas the rugged bark of the bur oak (Quercus macrocarpa) reflects its fire resistance.

The smooth bark of the American beech is a key ID characteristic, but also reflects this species' vulnerability to fire. Thick, rugged bark provides insulation to protect trees from fire. Beeches and other thin-barked trees thus tend to occur only in consistently-moist habitats that do not experience wildfires. Photo by Claire Secrist, Public Domain.

If you are managing a wild area for native plants, being able to reliably ID plants can tell you which species to remove and which to encourage. You can gather seeds from wild populations, and grow them in your garden, or get them established in wild areas you are working to restore.

Misidentification can have consequences. Some poisonous plants look disturbingly similar to common food plants, and some plants such as poison ivy can even be dangerous to touch. In many cases, native plants can look similar to closely-related invasive plants. Nurseries can mislabel plants, and cultivars can complicate matters by altering the characteristics typically used to identify plants. Even when plants are not invasive, a mis-identification can lead to growing something in a garden or landscape that is poorly suited to the site. A mis-ID'ed plant may die if planted in unsuitable conditions, or it may grow larger than wanted and require costly pruning or cause property damage.

Poison hemlock, pictured here, looks similar to parsley and carrots. This similarity can be dangerous because the plant is highly toxic. This plant belongs to the carrot family (Apiaceae) which is notorious for containing both poisonous plants and food plants, many of which are hard to tell apart.

Plant Comparison Guides: Side-by-Side Comparisons

With these purposes in mind, we are excited to announce our publishing of plant comparison guides!

Our plant comparison guides take two species that overlap in range and are commonly confused, and compare them side-by-side in a table.

This screenshot shows how the table appears on a desktop device or other device with a wide screen; the table collapses gracefully on small mobile devices as well.

How are we choosing which guides to write?

We have been using data from iNaturalist, a citizen science website and app, and focusing on plants that are commonly misidentified in photos on that site. One of the weaknesses of iNaturalist is that their site is littered with misidentifications, but this weakness can be turned into an asset because the site's active user base of casual users provides an excellent source of data on which plants are most commonly confused. Because the data comes from real observations in the wild, it also takes into account the increased likelihood of confusion based on plants whose ranges and habitat overlap.

However, even using iNaturalist as a guide, there are potentially thousands of these comparisons that we could be writing, so prioritization is critical. We want to write the guides that people most want to read. If you have a specific guide that you would like us to write, please get in touch!

Where can you find these guides on our site?

Currently, any published guides are displayed on the page for each species. There is a new "Similar Plants" section, and a link to it will be displayed in the table of contents at the top of each page that has such a section. This section is different from the "Related Plants" section that some articles have; the "similar plants" section is primarily for plants that are visually confused. They may or may not be related.

For example, Box Elder (Acer negundo) is a maple, but with its compound leaves it is more often confused with poison ivy or ash trees, and less frequently with other maples. Sugar Maple (Acer saccharum), on the other hand, has a more "typical" maple leaf and thus it is more often confused with other maples. Pictured here is the page of comparisons for sugar maple:

You can find completed comparison guides in the "Similar Species" section. Click "View" to be taken to the page for that species, or "Compare" to view the comparison and ID guide.

Check out the guides for yourself!

Here is a sampling of some of the guides we have completed:

We hope you enjoy these guides and find them useful!

And please send us your requests! You can ask us to make comparisons for a specific plant, a specific pair of plants, or a specific set of features for a pair of plants (such as if we haven't yet shown a picture of the bark, or flowers, or buds of a particular tree.)

And let us know if you have any corrections, find any major omissions, or have any photographs that you think could improve on our offerings. We want our ID guides to be as good as they can be!

Also, if you have not yet done so, please consider donating to support our work!