Pictures of Noxious Weeds

  • 01 of 14

    Pictures of Noxious Weeds

    Image: kudzu vine.
    Kudzu vine overwhelms all in its path, including trees. traveler1116/Getty Images

    "Noxious" weeds are so called because they are harmful (from the Latin, nocere, to harm). But harmful to whom and using what criteria to measure damage? Since, in the broadest sense, quite a variety of unwanted plants can be so classified, I try to approach the subject from a number of perspectives in these pictures.

    For instance, some people use the terminology "noxious weeds" as if it were almost synonymous with "invasive plants." And what criteria is used to measure the damage caused by invasive plants? Well, here are two sets of criteria:


    1. The amount of money wasted by farmers in trying to battle such noxious weeds, as they encroach upon farm land
    2. The number of native plants threatened as such noxious weeds encroach upon their wild habitats, out-competing them for resources

    In either of those two cases, after enough data is in, the noxious weeds in question will end up on one of the popular plant "blacklists," often organized by state (in the U.S.). Some states have even banned the importation of certain invasive plants, including Oriental bittersweet.

    But there are other senses in which unwanted plants may be classified as "noxious weeds." To name just 3 of them:


    1. If they are poisonous plants
    2. If they are plants that cause rashes
    3. If they cause allergies, as does common ragweed.

    the photo above is of kudzu vine, which is so notorious that it has earned the right to serve as the poster child for this topic. It has also earned the nickname, "the vine that ate the South," due to the way that it has voraciously spread through the Southeastern U.S. Known botanically as Pueraria montana, this plant is native to the Far East. According to the USDA Forest Service, kudzu vine reaches 35-100 feet in length and was introduced into the United States for, among other reasons, erosion control.

    Use the pictures of noxious weeds presented on the following pages to aid you in identification. On Page 2, we'll start with a noxious weed that causes allergies....

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  • 02 of 14

    What Does Ragweed Look Like?

    When ragweed plants come into bloom, allergy sufferers pay the price.
    When ragweed plants come into bloom, allergy sufferers pay the price. David Beaulieu

    Allergy sufferers will be quick to accept the classification of ragweed plants as "noxious weeds." Both common ragweed (pictured above) and giant ragweed are major contributors to hay fever.

    Ragweed season may be dreaded by young and old alike. Vincent Iannelli, M.D warns parents not to jump to the conclusion that a kid's runny nose in fall is the result of a virus picked up at school: it is possible that ragweed is to blame.

    Use my pictures and other resources to learn what ragweed looks like so that you can at least eliminate it from your own yard and thereby perhaps limit your exposure to the source of your hay-fever problems. Visit my gallery for more pictures of ragweed.

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  • 03 of 14

    Bittersweet Nightshade Berries

    Picture of bittersweet nightshade berries.
    Picture of bittersweet nightshade berries. David Beaulieu

    Bittersweet nightshade berries are toxic, making this poisonous plant (Solanum dulcamara) a "noxious weed" in my book any day! Don't confuse bittersweet nightshade with Celastrus orbiculatus plants, which are better known.

    Parents, you will want to identify bittersweet nightshade, scour your backyard for any plants that might be growing there, and remove them. The berries do not all ripen at the same time, meaning that a bittersweet nightshade plant can bear green, yellow, orange and red berries all at one time. This makes for a colorful display -- a display that could easily tempt young children into plucking them and eating them. I know, because I remember sampling bittersweet nightshade berries, myself as a child.

    I lived, obviously.

    But do you really want to take a chance? Furthermore, while, in many cases, toxic berries, leaves, etc. may cause nothing more severe than an upset stomach, you would still rather avoid that scenario if you could, right?

    So make it a practice to learn how to identify poisonous plants and remove them from your yard. And just in case you are unsuccessful in doing so and your kids ingest something that they should not, be prepared to call Poison Control.

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  • 04 of 14

    "Leaflets Three, Let It Be"

    This picture of poison ivy provides visual verification for the rhyme, 'Leaflets three, let it be.'
    This picture of poison ivy provides visual verification for the rhyme, 'Leaflets three, let it be.'. David Beaulieu

    You've heard the rhyme, "Leaflets three, let it be"? It's a rhyme to help you remember what poison ivy plant looks like. You will also hear the version, "Leaves of three, let it be." It means the same thing, but some sticklers prefer to refer to the individual parts of a compound leaf as "leaflets," while the less pedantic simply call them "leaves."

    Regardless of which version of the rhyme you like better, as you can see from this picture of poison ivy leaflets, the plant clearly does have leaflets or leaves of three parts. Knowing about the tripartite nature of poison ivy's foliage is a first step in identifying this rash-causing menace and keeping clear of it, so as to avoid coming down with the rash, in the first place, and thereby obviating the need for treatment of poison ivy rash. But other types of plants also have "leaves of three." So knowledge of this feature will get you only so far in truly being able to tell poison ivy from other plants.

    The next step for those interested in being able to differentiate this weed from vines that look like poison ivy is to study my poison ivy pictures, which show you what the plants look like at different times of the year (and, consequently, at different stages of growth).

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  • 05 of 14

    What Does Poison Sumac Look Like?

    Photo of fall foliage of poison sumac, showing red and pinkish leaves.
    This photo shows what poison sumac looks like in autumn, when its leaves are red or pinkish. David Beaulieu

    This picture shows you what poison sumac looks like. (Toxicodendron vernix) has a lovely autumn leaf color. Look, but do not touch! Contact with the plant can cause a rash that will be all too familiar to those who know what it is like to suffer with a rash from a related noxious weed, poison ivy.

    No need to become paranoid, though. Of the noxious weeds I cover here, poison sumac is perhaps the one that the average person is least likely to encounter in the yard. Why? Because it tends to grow in swampy areas. I had to conduct a web search just to learn where I could find some poison sumac shrubs in New England, so that I could take pictures of them (and inform my readers as to what poison sumac looks like, exactly). My web search led me to an obscure wetland in Andover, Massachusetts. This is a protected area, and the government built boardwalks through it so that the public can take a walk for some exercise and observe nature up close -- all without getting their feet wet! I was rewarded for my rather extreme efforts to locate some poison sumac with a terrific fall foliage display.

    Obviously, if it's plants with great fall foliage you wish to grow in your yard, you can make a safer choice than poison sumac. Still tempted by the colorful hues of poison sumac? Try the non-poisonous types of Rhus such as 'Tiger Eyes' (Rhus typhina 'Bailtiger') or plant other shrubs for fall color. Others will prefer to grow fall foliage trees.

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  • 06 of 14

    What Does Stinging Nettle Look Like?

    The flowers of stinging nettle are inconspicuous.
    Did you know that there is a verb, "to nettle," which means "to irritate?". David Beaulieu

    This picture shows what stinging nettle looks like in bloom.

    Sure, it's not much of a bloom -- I grant you that. There's no way it's going to make any of my galleries showing photos of colorful flowers. You probably won't be growing stinging nettle in your garden any time soon (on purpose), overwhelmed by its good looks. People interested in planting herbs may grow it in their gardens -- but for medicinal and culinary purposes, not because it's attractive!

    Brush up against the barbs of stinging nettle (Urtica dioica) and you'll soon feel a burning sensation. This weed causes a skin rash on contact. The severity of the rash may vary from person to person. I would categorize the results of my own brushes with stinging nettle as more of a nuisance than anything (although the discomfort can be rather severe, at first).

    Incidentally even when taking stinging nettle as an herbal medicine, you have to be mindful of its potential (as a side effect) to cause a rash.

    On the culinary side of the ledger, Molly Watson, Local Foods Expert, offers a recipe for making a stinging nettle soup. Personally, I have experience only with eating stinging nettle (when the leaves are young and tender) as a boiled green, the way one would eat spinach.

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  • 07 of 14

    Spotted Knapweed: A Centaurea That's a Noxious Weed

    Knapweed picture.
    Knapweed picture. David Beaulieu

    But enough of the noxious weeds that make my list for being toxic or causing rashes or allergies. Let's move on to some invasive plants, beginning with spotted knapweed.

    Spotted knapweed is an invasive biennial or perennial wildflower whose flower looks a bit like a thistle. Centaurea maculosa is the scientific name of the plant. Does that genus name sound familiar? It should, because there may well be plants in your landscaping classified as Centaurea (see next page).

    Farmers hate this plant for the negative impact it has on crops. Not only does spotted knapweed produce enormous amounts of seed, but, like the walnut tree (there are only certain plants that will grow under walnut trees), it is also alleopathic.

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  • 08 of 14

    Bull Thistle: Invasive Noxious Weed

    Thistle picture. Bull thistle is an invasive plant.
    Bull thistle is an invasive plant. David Beaulieu

    Not only is bull thistle (Cirsium vulgare) an invasive plant, but also, as indicated by the barbs in this picture, it can just plain hurt to run up against this plant! That's enough to put it on my "noxious weeds" list, any day. Some birdwatching enthusiasts do grow the plant, however, due to its ability to attract goldfinches.

    From the above picture of bull thistle, you may be able to tell that it is related to some of the perennials grown in the landscape. For example, it bears a strong resemblance to a yellow Centaurea sometimes referred to as "globe knapweed" (for a picture of spotted knapweed, see the photo on the prior page).

    Those of you familiar with the flora of overgrown pastures may know bull thistle as a common inhabitant of such areas. But this Old-World native can also take advantage of disturbed ground along, e.g., roadsides. No shy wallflower, you'll know this robust noxious weed when you see it: plants can reach a height of 7 feet under ideal conditions!

    Bull thistle is a biennial. It develops rosettes the first year, succeeded by flower stalks the following year. Plants are covered with spines, making the sort of spontaneous removal that you may practice with other noxious weeds a bad idea for bull thistle. No, this is the type of plant you come prepared to remove, wearing heavy gloves and long sleeves/pants and wielding a shovel. Dig bull thistle out by the root. Don't let it go to seed.

    The reason why letting it go to seed is such a bad idea is that the seeds of bull thistles, like those of dandelions and common milkweed, are easily transported across the air. Each seed is attached to thistledown, so it can travel far away from the mother plant when the wind blows.

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  • 09 of 14

    Japanese Knotweed Shoots: Godzillas in the Making

    Photo of young japanese knotweed.
    Photo of young Japanese knotweed shoots. David Beaulieu

    Elsewhere, I have nicknamed Japanese knotweed the "Godzilla weed." That's because this noxious weed (Polygonum cuspidatum) is the most difficult invasive plant to eradicate that you are ever likely to encounter! More typical nicknames you'll find for this plant are "Mexican bamboo" and "Japanese bamboo."

    The picture here shows what the new shoots look like. When its "bamboo shoots" first appear in spring, they can be considered edible weeds. I would be very cautious, though, in harvesting this plant for eating -- no matter how tender and nutritious the new shoots are supposed to be. The reason for my caution? Well, because this noxious weed is so difficult to get rid of, people have thrown everything but the kitchen sink at it over the years, in attempts to eliminate it. That includes toxic substances. So unless you are very familiar with the ground where a potential crop of Japanese knotweed is growing, I would err on the side of safety and refrain from harvesting it for culinary purposes.

    The tender Japanese bamboo shoots eventually harden as they grow taller, then die in winter, becoming brittle canes (the root system lives on underground, unfortunately). Even as new shoots in spring, though, they have the strength of Godzilla: many a time I have seen them exploiting cracks in concrete in urban areas to push there way up through sidewalks, driveways or paved parking lots.

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  • 10 of 14

    Honeysuckle Bush: Invasive Shrub

    Tartarian and morrow's honeysuckle are invasive shrubs.
    Honeysuckle bushes are tough customers, despite their sweet-sounding name. David Beaulieu

    Morrow's honeysuckle bushes (Lonicera morrowii) are indigenous to Eurasia, according to Marilyn J. Dwelley, author of Trees and Shrubs of New England (1980). It's hard to go anywhere in parts of New England without seeing them. They make my noxious weeds list on the basis of their invasiveness.

    Reaching 5-8 feet in height, Morrow's honeysuckle shrubs (not to be confused with Japanese honeysuckle vines) readily exploit disturbed soils to naturalize along roadsides and in thickets and open woods.

    Tatarian honeysuckle bushes (Lonicera tatarica) are, says Dwelley, native to Europe. The novice at plant identification has to take great pains to distinguish Morrow's honeysuckle bushes from the Tatarian version; these two shrubs are very similar in appearance. But let me give the beginner something simple to take away from this brief introduction: if you see a shrub such as the one pictured here, but with pink flowers, that plant is a Tatarian honeysuckle bush, because the flowers of Morrow's start out white and then become a creamy yellow. Both plants bloom in May-June.

    More importantly, take note that these are both invasive plants.

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  • 11 of 14

    Autumn Olive: Shrub That Escaped From Cultivation

    Picture of autumn olive.
    Picture of autumn olive. David Beaulieu

    Autumn olive may be confused, by the casual observer, with another noxious weed in this gallery, honeysuckle bushes (photo on prior page). The 2 share the same habitat.

    A shrub native to the Far East, autumn olive (Elaeagnus umbellata) is an invasive plant in North America. Effective at erosion control and salt tolerant, autumn olives were introduced into the U.S. for roadside plantings. They later escaped from cultivation.

    Autumn olive is very similar in appearance to another invasive shrub or small tree, Russian olive (Elaeagnus angustifolia). Both have silvery leaves; but autumn olive's leaves are usually silvery only on the underside. Another way to distinguish between autumn olive and Russian olive is to inspect the shape of their respective leaves. Russian olive bears a narrower leaf than the leaf you see in my picture of autumn olive, above; thus its species name, angustifolia, which means "narrow-leafed" in Latin.

    Incidentally, the specific epithet for autumn olive, umbellata refers to the "umbels" of flowers borne by autumn olive shrubs (an "umbel" being a flower head wherein the individual flower stalks are of about the same length, radiating out of the center like the spokes of an umbrella).

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  • 12 of 14

    Tree of Heaven and "A Tree Grows in Brooklyn"

    Picture of tree of heaven.
    Picture of tree of heaven. David Beaulieu


    Tree of heaven is the common name for Ailanthus altissima. This invasive plant is also known as "Chinese sumac." Why? Because it is indigenous to China and it resembles the sumac native to North America.

    As Steve Nix notes, tree of heaven, a tree sometimes ubiquitous in urban areas, was the inspiration behind A Tree Grows in Brooklyn, by Betty Smith. One person's noxious weed is another's inspiration!

    Not that I am totally surprised that tree of heaven could have inspired A Tree Grows in Brooklyn. Noxious weed or not, the seed clusters on tree of heaven are rather pleasing to the eye.

    While this resource on noxious plants has focused on weedy plants, that does not mean that "legitimate" landscape plants are always beyond reproach. If growing such a specimen were to result in the poisoning of a child, the parents of that child would understandably consider it a "noxious plant" of sorts. I give an egregious example on the following page.

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  • 13 of 14

    Monkshood (Wolfsbane): Member of the Buttercup Family

    Image of the leaves of monkshood.
    The leaves of monkshood betray the fact that it belongs to the buttercup family. David Beaulieu

    Monkshood (Aconitum) is no weed but, rather, a fairly popular landscape plant. It is a perennial commonly used in flower borders, valued for its purple flowers. So, in my picture, why am I showing you what the foliage looks like, rather than the flowers?

    I do so because I present monkshood here not to discuss its beauty but to warn you about its toxicity (making it a "noxious plant" on one level). Once you understand that a plant is toxic, the next logical question (assuming that its toxicity concerns you) to ask is, "What does it look like?" And the fact of the matter is that leaves are more useful for identification purposes than are flowers, simply because leaves are usually present for a longer period of time each year than are flowers. 

    Take a good, close look at the leaves in my photo. You may notice how closely the leaves resemble those of delphinium plants. Indeed, delphinium and monkshood are both in the Ranunculaceae or "buttercup" family. The plants of this family are notorious for harboring a toxin called "protoanemonin." If you have young kids in your household, you may want to avoid growing monkshood, for fear that your kids might eat this poisonous plant.

    "Monkshood" is a reference to this perennial's flower. Those imaginative folks who have given plants their common names over the centuries fancied that the shape of the flower mimics that of the hood on a garment traditionally worn by monks.

    Fewer and fewer people can relate to "monkshood" as a common name. "Wolfsbane" is not much better, considering that not many people have wolves running around in their neighborhoods these days. The "bane," however, does, at least, warn you of its toxicity.

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  • 14 of 14


    Image of dogbane plant.
    Dogbane, as its name suggests, is poisonous to dogs. David Beaulieu

    Dogbane (Apocynum cannabinum) goes by a number of other common names, including "hemp dogbane." While Apocynum cannabinum is the type native to North America, there are other kinds of dogbane native to the Old World. As with wolfsbane (monkshood) in the prior entry, the reason for me to include this weed on my list of noxious weeds is present in its very name ("bane" indicating that something is harmful). While that name identifies dogs, specifically, as the potential victims, dogbane is actually considered poisonous in a more general sense (that is, toxic to other life forms), as well.