what weed is it? putting names to pesky plants

garlic-mustardI KNOW A LOT OF PLANTS BY THEIR PROPER NAMES, but when it comes to “weeds,” as we term unwanted garden visitors that seem to just come with the territory, my knowledge really pales. So lately, on days not conducive to outdoor work, I’ve been studying up a bit from some great weed-identification websites, so that I can finally address Alliaria petiolata (garlic mustard, above) with the proper (dis)respect.

I didn’t even remember the botanical Latin name for the ubiquitous dandelion, Taraxacum officinale, below, until I became a regular on the Rutgers New Jersey Agricultural Experiment Station “weed gallery” recently. What I love about the Rutgers weed tool, besides its general appropriateness for my garden regionally speaking, is that I can browse by common names or by thumbnail photos (or by Latin names if I ever know one).

dandelion 3
The University of Minnesota’s “Is This Plant a Weed?” tool is another place you’ll find me, narrowing the field of possibilities until I get an ID by clicking through a series of photo-based prompts (such as grass or broadleaf….upright or creeping…and so on). It almost makes weeds fun. (Note the almost.)

Steve Brill, the so-called “Wildman” forager who teaches in Central Park in New York City and elsewhere, has a chart and plant profiles of edible weeds on his website, if you’re hungry, though you’ll have to scroll a third of the way down the homepage and click on “wild plants” (fourth blue box from the top) to get there. Once you do, you can serve up Japanese knotweed, dandelion greens and even plantain (though the latter’s not so tasty, below; Plantago major is better used on mosquito bites than on a dinner plate).

The University of California-Davis weed ID site is encyclopedic, and though I wish I could sort by images, once I get to them (on the plant profile pages) the information is some of the most detailed anywhere. They even show the weed in its seedling stage so you can eradicate it then without wondering if it’s your beloved self-sown something-or-other. See what I mean on a sample page (this one is bedstraw, Galium aparine, a common weed here as well).

With 172 species included, the University of Illinois has built an extensive weed database that’s browsable by common or Latin names, but with the added feature of filters (you can sort the list down to a certain flower color, for instance, or one of a series of very specific taxonomic keys, like leaf size, width, or the arrangement of the leaves. This one will get you sharpening your powers of observation.

I own a number of weed guides, some more booklet-sized than book, and was happy to find a full-color one posted free online. “Weeds of the North Central States” is available as a PDF to “page” through, should you happen to live in them there states.

Want to know which ones are so bad they have made their names on the state-by-state “noxious weeds” lists? The real Bad Boys of Weed-dom.

As many weeds as there are, there are apparently as many sources to learn about then. I could go on, but then you’d think I’d grown a bit obsessed with weeds at the moment, wouldn’t you?

April 21, 2010


  1. Ellie says

    The bane of my garden is Glechoma hederacea, aka ground ivy or “creeping Charlie”. I will dig out a huge patch of it and it’s back within weeks.

    Of the weeds I actually planted, I am guilty of inflicting Blue Fortune agastache and chocolate (white flowered) Joe Pye weed all over my garden.

    And then there are the wild violets. Everywhere!

  2. Rae says

    I am so happy to find a weed which has spread in my front garden – buckhorn plantain. It faked the stokesias I have there perfectly until it flowered. I can now see the babies which are like a small lettuce. Thanks for the Illinois list link, Margaret.

  3. says

    Thank you for the id of clearweed on another post. It is in my garden, too, and was driving me nuts that I couldn’t name it. (I do so understand your desire to identify your weeds.) Since there are over 100 comments on this post which I’m not going to read through, I may be repeating someone else. But I wanted to share two other weed identification sites I’ve found: http://weedid.wisc.edu/weedid.php and https://gobotany.newenglandwild.org/advanced/ . Thanks!

    • margaret says

      Hi, Kathy. Yes, clearweed as a familiar resident here for years before I figured out who it was! Thanks for the added sites to search.

  4. Kathy says

    Yes, the id of clear weed is very helpful,. And as do many of you I have lots and never knew what it was.
    Be gentle with the “weeds”. Many of them are helpful herbs.

    • margaret says

      Agree, Kathy — important to leave enough for pollinators and other insects, but not in the beds where you are growing vegetables or formal areas, of course. I like to have rough, unmown areas of the yard that support wildlife where anything goes, contrasted against the more “garden-y” beds and borders.

  5. Shelley says

    Is there a comprehensive pictorial on weeds? I have what I think is pig weed plus some other nagging problem weeds but am unsure what they are and, therefore, how to deal with them. What would help a lot are pictures of all weeds in my area (Pacific NW, Eastern Oregon).
    This weeds grows along the ground and has red stems. I think it’s an annual.

    Your blog is the most reliable source on so many things that I come to you for help. Help! :)

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